diff --git a/.clang-tidy b/.clang-tidy
index 4e128a19455..9aeeb1fc26c 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -96,7 +96,6 @@ Checks: >-
   -modernize-avoid-variadic-functions,
   -modernize-avoid-c-arrays,
   -modernize-avoid-c-style-cast,
-  -modernize-concat-nested-namespaces,
   -modernize-macro-to-enum,
   -modernize-return-braced-init-list,
   -modernize-type-traits,
diff --git a/.clang-tidy.hash b/.clang-tidy.hash
index 582e0c1eaa2..2f973e34d9f 100644
--- a/.clang-tidy.hash
+++ b/.clang-tidy.hash
@@ -1 +1 @@
-0c7f309d70eca8e3efd510092ddb23c530f3934c49371717efa124b788d761f8
+c1e4375738304baabf7e915e5f7ca50fb22ec9b4a2d8312827a32a659f3fa40c
diff --git a/esphome/components/adc/adc_sensor_esp8266.cpp b/esphome/components/adc/adc_sensor_esp8266.cpp
index be14b252d43..e4f2f82f085 100644
--- a/esphome/components/adc/adc_sensor_esp8266.cpp
+++ b/esphome/components/adc/adc_sensor_esp8266.cpp
@@ -11,8 +11,7 @@ ADC_MODE(ADC_VCC)
 #include <Arduino.h>
 #endif  // USE_ADC_SENSOR_VCC
 
-namespace esphome {
-namespace adc {
+namespace esphome::adc {
 
 static const char *const TAG = "adc.esp8266";
 
@@ -55,7 +54,6 @@ float ADCSensor::sample() {
   return aggr.aggregate() / 1024.0f;
 }
 
-}  // namespace adc
-}  // namespace esphome
+}  // namespace esphome::adc
 
 #endif  // USE_ESP8266
diff --git a/esphome/components/adc/adc_sensor_libretiny.cpp b/esphome/components/adc/adc_sensor_libretiny.cpp
index 0b1393c2e70..d9b9f50be1f 100644
--- a/esphome/components/adc/adc_sensor_libretiny.cpp
+++ b/esphome/components/adc/adc_sensor_libretiny.cpp
@@ -3,8 +3,7 @@
 #include "adc_sensor.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace adc {
+namespace esphome::adc {
 
 static const char *const TAG = "adc.libretiny";
 
@@ -48,7 +47,6 @@ float ADCSensor::sample() {
   return aggr.aggregate() / 1000.0f;
 }
 
-}  // namespace adc
-}  // namespace esphome
+}  // namespace esphome::adc
 
 #endif  // USE_LIBRETINY
diff --git a/esphome/components/adc/adc_sensor_rp2040.cpp b/esphome/components/adc/adc_sensor_rp2040.cpp
index a79707e2347..8d41edb8145 100644
--- a/esphome/components/adc/adc_sensor_rp2040.cpp
+++ b/esphome/components/adc/adc_sensor_rp2040.cpp
@@ -15,8 +15,7 @@
 #define PICO_VSYS_PIN 29  // NOLINT(cppcoreguidelines-macro-usage)
 #endif
 
-namespace esphome {
-namespace adc {
+namespace esphome::adc {
 
 static const char *const TAG = "adc.rp2040";
 
@@ -98,7 +97,6 @@ float ADCSensor::sample() {
   return aggr.aggregate() * 3.3f / 4096.0f * coeff;
 }
 
-}  // namespace adc
-}  // namespace esphome
+}  // namespace esphome::adc
 
 #endif  // USE_RP2040
diff --git a/esphome/components/adc/adc_sensor_zephyr.cpp b/esphome/components/adc/adc_sensor_zephyr.cpp
index 2fb9d4b0e50..c3632b00e20 100644
--- a/esphome/components/adc/adc_sensor_zephyr.cpp
+++ b/esphome/components/adc/adc_sensor_zephyr.cpp
@@ -5,8 +5,7 @@
 
 #include "hal/nrf_saadc.h"
 
-namespace esphome {
-namespace adc {
+namespace esphome::adc {
 
 static const char *const TAG = "adc.zephyr";
 
@@ -202,6 +201,5 @@ float ADCSensor::sample() {
   return val_mv / 1000.0f;
 }
 
-}  // namespace adc
-}  // namespace esphome
+}  // namespace esphome::adc
 #endif
diff --git a/esphome/components/beken_spi_led_strip/led_strip.cpp b/esphome/components/beken_spi_led_strip/led_strip.cpp
index f425f3ca5c4..4e22489844b 100644
--- a/esphome/components/beken_spi_led_strip/led_strip.cpp
+++ b/esphome/components/beken_spi_led_strip/led_strip.cpp
@@ -33,8 +33,7 @@ static const uint32_t CTRL_NSSMD_3 = 1 << 17;
 static const uint32_t SPI_TX_FINISH_EN = 1 << 2;
 static const uint32_t SPI_RX_FINISH_EN = 1 << 3;
 
-namespace esphome {
-namespace beken_spi_led_strip {
+namespace esphome::beken_spi_led_strip {
 
 static const char *const TAG = "beken_spi_led_strip";
 
@@ -382,7 +381,6 @@ void BekenSPILEDStripLightOutput::dump_config() {
 
 float BekenSPILEDStripLightOutput::get_setup_priority() const { return setup_priority::HARDWARE; }
 
-}  // namespace beken_spi_led_strip
-}  // namespace esphome
+}  // namespace esphome::beken_spi_led_strip
 
 #endif  // USE_BK72XX
diff --git a/esphome/components/beken_spi_led_strip/led_strip.h b/esphome/components/beken_spi_led_strip/led_strip.h
index 705f9102a99..4ed640a3bc4 100644
--- a/esphome/components/beken_spi_led_strip/led_strip.h
+++ b/esphome/components/beken_spi_led_strip/led_strip.h
@@ -8,8 +8,7 @@
 #include "esphome/core/component.h"
 #include "esphome/core/helpers.h"
 
-namespace esphome {
-namespace beken_spi_led_strip {
+namespace esphome::beken_spi_led_strip {
 
 enum RGBOrder : uint8_t {
   ORDER_RGB,
@@ -79,7 +78,6 @@ class BekenSPILEDStripLightOutput : public light::AddressableLight {
   optional<uint32_t> max_refresh_rate_{};
 };
 
-}  // namespace beken_spi_led_strip
-}  // namespace esphome
+}  // namespace esphome::beken_spi_led_strip
 
 #endif  // USE_BK72XX
diff --git a/esphome/components/bme68x_bsec2_i2c/bme68x_bsec2_i2c.cpp b/esphome/components/bme68x_bsec2_i2c/bme68x_bsec2_i2c.cpp
index 2d74ba6b122..2a2c5e2bcc8 100644
--- a/esphome/components/bme68x_bsec2_i2c/bme68x_bsec2_i2c.cpp
+++ b/esphome/components/bme68x_bsec2_i2c/bme68x_bsec2_i2c.cpp
@@ -9,8 +9,7 @@
 
 #include <cinttypes>
 
-namespace esphome {
-namespace bme68x_bsec2_i2c {
+namespace esphome::bme68x_bsec2_i2c {
 
 static const char *const TAG = "bme68x_bsec2_i2c.sensor";
 
@@ -53,6 +52,5 @@ void BME68xBSEC2I2CComponent::delay_us(uint32_t period, void *intfPtr) {
   delayMicroseconds(period);
 }
 
-}  // namespace bme68x_bsec2_i2c
-}  // namespace esphome
+}  // namespace esphome::bme68x_bsec2_i2c
 #endif
diff --git a/esphome/components/bme68x_bsec2_i2c/bme68x_bsec2_i2c.h b/esphome/components/bme68x_bsec2_i2c/bme68x_bsec2_i2c.h
index a21a123f7b9..6d20b613903 100644
--- a/esphome/components/bme68x_bsec2_i2c/bme68x_bsec2_i2c.h
+++ b/esphome/components/bme68x_bsec2_i2c/bme68x_bsec2_i2c.h
@@ -9,8 +9,7 @@
 #include "esphome/components/bme68x_bsec2/bme68x_bsec2.h"
 #include "esphome/components/i2c/i2c.h"
 
-namespace esphome {
-namespace bme68x_bsec2_i2c {
+namespace esphome::bme68x_bsec2_i2c {
 
 class BME68xBSEC2I2CComponent : public bme68x_bsec2::BME68xBSEC2Component, public i2c::I2CDevice {
   void setup() override;
@@ -23,6 +22,5 @@ class BME68xBSEC2I2CComponent : public bme68x_bsec2::BME68xBSEC2Component, publi
   static void delay_us(uint32_t period, void *intfPtr);
 };
 
-}  // namespace bme68x_bsec2_i2c
-}  // namespace esphome
+}  // namespace esphome::bme68x_bsec2_i2c
 #endif
diff --git a/esphome/components/debug/debug_esp8266.cpp b/esphome/components/debug/debug_esp8266.cpp
index 0519ab72fe9..272123dfc0e 100644
--- a/esphome/components/debug/debug_esp8266.cpp
+++ b/esphome/components/debug/debug_esp8266.cpp
@@ -15,8 +15,7 @@ extern uint32_t core_version;
 extern const char *core_release;
 }
 
-namespace esphome {
-namespace debug {
+namespace esphome::debug {
 
 static const char *const TAG = "debug";
 
@@ -170,6 +169,5 @@ void DebugComponent::update_platform_() {
 #endif
 }
 
-}  // namespace debug
-}  // namespace esphome
+}  // namespace esphome::debug
 #endif
diff --git a/esphome/components/debug/debug_host.cpp b/esphome/components/debug/debug_host.cpp
index 0dfab86e4c4..298a7e44e70 100644
--- a/esphome/components/debug/debug_host.cpp
+++ b/esphome/components/debug/debug_host.cpp
@@ -2,8 +2,7 @@
 #ifdef USE_HOST
 #include <climits>
 
-namespace esphome {
-namespace debug {
+namespace esphome::debug {
 
 const char *DebugComponent::get_reset_reason_(std::span<char, RESET_REASON_BUFFER_SIZE> buffer) { return ""; }
 
@@ -15,6 +14,5 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
 
 void DebugComponent::update_platform_() {}
 
-}  // namespace debug
-}  // namespace esphome
+}  // namespace esphome::debug
 #endif
diff --git a/esphome/components/debug/debug_libretiny.cpp b/esphome/components/debug/debug_libretiny.cpp
index 6f36debb95a..1cc04dcbd8e 100644
--- a/esphome/components/debug/debug_libretiny.cpp
+++ b/esphome/components/debug/debug_libretiny.cpp
@@ -2,8 +2,7 @@
 #ifdef USE_LIBRETINY
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace debug {
+namespace esphome::debug {
 
 static const char *const TAG = "debug";
 
@@ -62,6 +61,5 @@ void DebugComponent::update_platform_() {
 #endif
 }
 
-}  // namespace debug
-}  // namespace esphome
+}  // namespace esphome::debug
 #endif
diff --git a/esphome/components/debug/debug_rp2040.cpp b/esphome/components/debug/debug_rp2040.cpp
index 73f08492c86..adc23dbf51f 100644
--- a/esphome/components/debug/debug_rp2040.cpp
+++ b/esphome/components/debug/debug_rp2040.cpp
@@ -12,8 +12,7 @@
 #ifdef USE_RP2040_CRASH_HANDLER
 #include "esphome/components/rp2040/crash_handler.h"
 #endif
-namespace esphome {
-namespace debug {
+namespace esphome::debug {
 
 static const char *const TAG = "debug";
 
@@ -84,6 +83,5 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
 
 void DebugComponent::update_platform_() {}
 
-}  // namespace debug
-}  // namespace esphome
+}  // namespace esphome::debug
 #endif
diff --git a/esphome/components/deep_sleep/deep_sleep_esp8266.cpp b/esphome/components/deep_sleep/deep_sleep_esp8266.cpp
index 42c153c2f38..9239a7fb311 100644
--- a/esphome/components/deep_sleep/deep_sleep_esp8266.cpp
+++ b/esphome/components/deep_sleep/deep_sleep_esp8266.cpp
@@ -3,8 +3,7 @@
 
 #include <Esp.h>
 
-namespace esphome {
-namespace deep_sleep {
+namespace esphome::deep_sleep {
 
 static const char *const TAG = "deep_sleep";
 
@@ -20,6 +19,5 @@ void DeepSleepComponent::deep_sleep_() {
 
 bool DeepSleepComponent::should_teardown_() { return true; }
 
-}  // namespace deep_sleep
-}  // namespace esphome
+}  // namespace esphome::deep_sleep
 #endif
diff --git a/esphome/components/esp8266_pwm/esp8266_pwm.cpp b/esphome/components/esp8266_pwm/esp8266_pwm.cpp
index cc6bfbc8a88..b5b3d5073aa 100644
--- a/esphome/components/esp8266_pwm/esp8266_pwm.cpp
+++ b/esphome/components/esp8266_pwm/esp8266_pwm.cpp
@@ -8,8 +8,7 @@
 
 #include <core_esp8266_waveform.h>
 
-namespace esphome {
-namespace esp8266_pwm {
+namespace esphome::esp8266_pwm {
 
 static const char *const TAG = "esp8266_pwm";
 
@@ -53,7 +52,6 @@ void HOT ESP8266PWM::write_state(float state) {
   }
 }
 
-}  // namespace esp8266_pwm
-}  // namespace esphome
+}  // namespace esphome::esp8266_pwm
 
 #endif
diff --git a/esphome/components/esp8266_pwm/esp8266_pwm.h b/esphome/components/esp8266_pwm/esp8266_pwm.h
index 4b021fc4622..51c4ea16028 100644
--- a/esphome/components/esp8266_pwm/esp8266_pwm.h
+++ b/esphome/components/esp8266_pwm/esp8266_pwm.h
@@ -7,8 +7,7 @@
 #include "esphome/core/automation.h"
 #include "esphome/components/output/float_output.h"
 
-namespace esphome {
-namespace esp8266_pwm {
+namespace esphome::esp8266_pwm {
 
 class ESP8266PWM : public output::FloatOutput, public Component {
  public:
@@ -48,7 +47,6 @@ template<typename... Ts> class SetFrequencyAction : public Action<Ts...> {
   ESP8266PWM *parent_;
 };
 
-}  // namespace esp8266_pwm
-}  // namespace esphome
+}  // namespace esphome::esp8266_pwm
 
 #endif
diff --git a/esphome/components/esp_ldo/esp_ldo.cpp b/esphome/components/esp_ldo/esp_ldo.cpp
index f8ebec19035..b3c9a59865d 100644
--- a/esphome/components/esp_ldo/esp_ldo.cpp
+++ b/esphome/components/esp_ldo/esp_ldo.cpp
@@ -3,8 +3,7 @@
 #include "esphome/core/log.h"
 #include "esphome/core/helpers.h"
 
-namespace esphome {
-namespace esp_ldo {
+namespace esphome::esp_ldo {
 
 static const char *const TAG = "esp_ldo";
 void EspLdo::setup() {
@@ -41,7 +40,6 @@ void EspLdo::adjust_voltage(float voltage) {
   }
 }
 
-}  // namespace esp_ldo
-}  // namespace esphome
+}  // namespace esphome::esp_ldo
 
 #endif  // USE_ESP32_VARIANT_ESP32P4
diff --git a/esphome/components/esp_ldo/esp_ldo.h b/esphome/components/esp_ldo/esp_ldo.h
index 1a20f1d08ad..bb1579e83dd 100644
--- a/esphome/components/esp_ldo/esp_ldo.h
+++ b/esphome/components/esp_ldo/esp_ldo.h
@@ -4,8 +4,7 @@
 #include "esphome/core/automation.h"
 #include "esp_ldo_regulator.h"
 
-namespace esphome {
-namespace esp_ldo {
+namespace esphome::esp_ldo {
 
 class EspLdo : public Component {
  public:
@@ -40,7 +39,6 @@ template<typename... Ts> class AdjustAction : public Action<Ts...> {
   EspLdo *ldo_;
 };
 
-}  // namespace esp_ldo
-}  // namespace esphome
+}  // namespace esphome::esp_ldo
 
 #endif  // USE_ESP32_VARIANT_ESP32P4
diff --git a/esphome/components/host/gpio.h b/esphome/components/host/gpio.h
index ea6b13f436e..6f2bccf1021 100644
--- a/esphome/components/host/gpio.h
+++ b/esphome/components/host/gpio.h
@@ -4,8 +4,7 @@
 
 #include "esphome/core/hal.h"
 
-namespace esphome {
-namespace host {
+namespace esphome::host {
 
 class HostGPIOPin : public InternalGPIOPin {
  public:
@@ -32,7 +31,6 @@ class HostGPIOPin : public InternalGPIOPin {
   gpio::Flags flags_{};
 };
 
-}  // namespace host
-}  // namespace esphome
+}  // namespace esphome::host
 
 #endif  // USE_HOST
diff --git a/esphome/components/libretiny_pwm/libretiny_pwm.cpp b/esphome/components/libretiny_pwm/libretiny_pwm.cpp
index 4e4a16d761f..eea593a39da 100644
--- a/esphome/components/libretiny_pwm/libretiny_pwm.cpp
+++ b/esphome/components/libretiny_pwm/libretiny_pwm.cpp
@@ -3,8 +3,7 @@
 
 #ifdef USE_LIBRETINY
 
-namespace esphome {
-namespace libretiny_pwm {
+namespace esphome::libretiny_pwm {
 
 static const char *const TAG = "libretiny.pwm";
 
@@ -49,7 +48,6 @@ void LibreTinyPWM::update_frequency(float frequency) {
   this->write_state(this->duty_);
 }
 
-}  // namespace libretiny_pwm
-}  // namespace esphome
+}  // namespace esphome::libretiny_pwm
 
 #endif
diff --git a/esphome/components/libretiny_pwm/libretiny_pwm.h b/esphome/components/libretiny_pwm/libretiny_pwm.h
index f9117090548..f7737be386b 100644
--- a/esphome/components/libretiny_pwm/libretiny_pwm.h
+++ b/esphome/components/libretiny_pwm/libretiny_pwm.h
@@ -7,8 +7,7 @@
 
 #ifdef USE_LIBRETINY
 
-namespace esphome {
-namespace libretiny_pwm {
+namespace esphome::libretiny_pwm {
 
 class LibreTinyPWM : public output::FloatOutput, public Component {
  public:
@@ -49,7 +48,6 @@ template<typename... Ts> class SetFrequencyAction : public Action<Ts...> {
   LibreTinyPWM *parent_;
 };
 
-}  // namespace libretiny_pwm
-}  // namespace esphome
+}  // namespace esphome::libretiny_pwm
 
 #endif
diff --git a/esphome/components/light/light_traits.h b/esphome/components/light/light_traits.h
index c3bb27a9647..a2a6b0a916b 100644
--- a/esphome/components/light/light_traits.h
+++ b/esphome/components/light/light_traits.h
@@ -3,15 +3,7 @@
 #include "color_mode.h"
 #include "esphome/core/helpers.h"
 
-namespace esphome {
-
-#ifdef USE_API
-namespace api {
-class APIConnection;
-}  // namespace api
-#endif
-
-namespace light {
+namespace esphome::light {
 
 /// This class is used to represent the capabilities of a light.
 class LightTraits {
@@ -43,5 +35,4 @@ class LightTraits {
   ColorModeMask supported_color_modes_{};
 };
 
-}  // namespace light
-}  // namespace esphome
+}  // namespace esphome::light
diff --git a/esphome/components/lightwaverf/LwRx.cpp b/esphome/components/lightwaverf/LwRx.cpp
index 97104578508..dfb8edfaf7a 100644
--- a/esphome/components/lightwaverf/LwRx.cpp
+++ b/esphome/components/lightwaverf/LwRx.cpp
@@ -10,8 +10,7 @@
 #include <cstring>
 #include "esphome/core/helpers.h"
 
-namespace esphome {
-namespace lightwaverf {
+namespace esphome::lightwaverf {
 
 /**
   Pin change interrupt routine that identifies 1 and 0 LightwaveRF bits
@@ -430,6 +429,5 @@ void LwRx::rx_remove_pair_(uint8_t *buf) {
   }
 }
 
-}  // namespace lightwaverf
-}  // namespace esphome
+}  // namespace esphome::lightwaverf
 #endif
diff --git a/esphome/components/lightwaverf/LwTx.cpp b/esphome/components/lightwaverf/LwTx.cpp
index 8852935bfd8..339980d6ee6 100644
--- a/esphome/components/lightwaverf/LwTx.cpp
+++ b/esphome/components/lightwaverf/LwTx.cpp
@@ -11,8 +11,7 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace lightwaverf {
+namespace esphome::lightwaverf {
 
 static const uint8_t TX_NIBBLE[] = {0xF6, 0xEE, 0xED, 0xEB, 0xDE, 0xDD, 0xDB, 0xBE,
                                     0xBD, 0xBB, 0xB7, 0x7E, 0x7D, 0x7B, 0x77, 0x6F};
@@ -208,6 +207,5 @@ void LwTx::lw_timer_stop() {
   }
 }
 
-}  // namespace lightwaverf
-}  // namespace esphome
+}  // namespace esphome::lightwaverf
 #endif
diff --git a/esphome/components/lightwaverf/lightwaverf.cpp b/esphome/components/lightwaverf/lightwaverf.cpp
index 2c6a1ecf5b5..b8b6a9697ea 100644
--- a/esphome/components/lightwaverf/lightwaverf.cpp
+++ b/esphome/components/lightwaverf/lightwaverf.cpp
@@ -5,8 +5,7 @@
 
 #include "lightwaverf.h"
 
-namespace esphome {
-namespace lightwaverf {
+namespace esphome::lightwaverf {
 
 static const char *const TAG = "lightwaverf.sensor";
 
@@ -62,7 +61,6 @@ void LightWaveRF::dump_config() {
   LOG_PIN("  Pin RX: ", this->pin_rx_);
   LOG_UPDATE_INTERVAL(this);
 }
-}  // namespace lightwaverf
-}  // namespace esphome
+}  // namespace esphome::lightwaverf
 
 #endif
diff --git a/esphome/components/lightwaverf/lightwaverf.h b/esphome/components/lightwaverf/lightwaverf.h
index 6210e6b5d47..224da6315f4 100644
--- a/esphome/components/lightwaverf/lightwaverf.h
+++ b/esphome/components/lightwaverf/lightwaverf.h
@@ -11,8 +11,7 @@
 #include "LwRx.h"
 #include "LwTx.h"
 
-namespace esphome {
-namespace lightwaverf {
+namespace esphome::lightwaverf {
 
 #ifdef USE_ESP8266
 
@@ -61,6 +60,5 @@ template<typename... Ts> class SendRawAction : public Action<Ts...> {
 };
 
 #endif
-}  // namespace lightwaverf
-}  // namespace esphome
+}  // namespace esphome::lightwaverf
 #endif
diff --git a/esphome/components/midea/ir_transmitter.h b/esphome/components/midea/ir_transmitter.h
index a16aed2e722..f11682230d3 100644
--- a/esphome/components/midea/ir_transmitter.h
+++ b/esphome/components/midea/ir_transmitter.h
@@ -4,8 +4,7 @@
 #ifdef USE_REMOTE_TRANSMITTER
 #include "esphome/components/remote_base/midea_protocol.h"
 
-namespace esphome {
-namespace midea {
+namespace esphome::midea {
 
 using remote_base::RemoteTransmitterBase;
 using IrData = remote_base::MideaData;
@@ -84,8 +83,7 @@ class IrTransmitter {
   RemoteTransmitterBase *transmitter_{nullptr};
 };
 
-}  // namespace midea
-}  // namespace esphome
+}  // namespace esphome::midea
 
 #endif
 #endif  // USE_ARDUINO
diff --git a/esphome/components/mipi_dsi/mipi_dsi.cpp b/esphome/components/mipi_dsi/mipi_dsi.cpp
index fc59aeffe89..9bd2dded2c8 100644
--- a/esphome/components/mipi_dsi/mipi_dsi.cpp
+++ b/esphome/components/mipi_dsi/mipi_dsi.cpp
@@ -3,8 +3,7 @@
 #include "mipi_dsi.h"
 #include "esphome/core/helpers.h"
 
-namespace esphome {
-namespace mipi_dsi {
+namespace esphome::mipi_dsi {
 
 // Maximum bytes to log for init commands (truncated if larger)
 static constexpr size_t MIPI_DSI_MAX_CMD_LOG_BYTES = 64;
@@ -411,6 +410,5 @@ void MIPI_DSI::dump_config() {
                 YESNO(this->invert_colors_), this->pclk_frequency_);
   LOG_PIN("  Reset Pin ", this->reset_pin_);
 }
-}  // namespace mipi_dsi
-}  // namespace esphome
+}  // namespace esphome::mipi_dsi
 #endif  // USE_ESP32_VARIANT_ESP32P4
diff --git a/esphome/components/mipi_dsi/mipi_dsi.h b/esphome/components/mipi_dsi/mipi_dsi.h
index c27c9ccc6ef..82827d813e8 100644
--- a/esphome/components/mipi_dsi/mipi_dsi.h
+++ b/esphome/components/mipi_dsi/mipi_dsi.h
@@ -16,8 +16,7 @@
 
 #include "esp_lcd_mipi_dsi.h"
 
-namespace esphome {
-namespace mipi_dsi {
+namespace esphome::mipi_dsi {
 
 constexpr static const char *const TAG = "display.mipi_dsi";
 const uint8_t SW_RESET_CMD = 0x01;
@@ -113,6 +112,5 @@ class MIPI_DSI : public display::Display {
   uint16_t y_high_{0};
 };
 
-}  // namespace mipi_dsi
-}  // namespace esphome
+}  // namespace esphome::mipi_dsi
 #endif
diff --git a/esphome/components/mipi_rgb/mipi_rgb.cpp b/esphome/components/mipi_rgb/mipi_rgb.cpp
index 6f5e2f2490c..b07460fdba9 100644
--- a/esphome/components/mipi_rgb/mipi_rgb.cpp
+++ b/esphome/components/mipi_rgb/mipi_rgb.cpp
@@ -8,8 +8,7 @@
 #include <esp_lcd_panel_rgb.h>
 #include <span>
 
-namespace esphome {
-namespace mipi_rgb {
+namespace esphome::mipi_rgb {
 
 static const uint8_t DELAY_FLAG = 0xFF;
 
@@ -400,6 +399,5 @@ void MipiRgb::dump_config() {
   this->dump_pins_(3, 8, "Red", 0);
 }
 
-}  // namespace mipi_rgb
-}  // namespace esphome
+}  // namespace esphome::mipi_rgb
 #endif  // defined(USE_ESP32_VARIANT_ESP32S3) || defined(USE_ESP32_VARIANT_ESP32P4)
diff --git a/esphome/components/mipi_rgb/mipi_rgb.h b/esphome/components/mipi_rgb/mipi_rgb.h
index accc251a184..4d1d8360998 100644
--- a/esphome/components/mipi_rgb/mipi_rgb.h
+++ b/esphome/components/mipi_rgb/mipi_rgb.h
@@ -8,8 +8,7 @@
 #include "esphome/components/spi/spi.h"
 #endif
 
-namespace esphome {
-namespace mipi_rgb {
+namespace esphome::mipi_rgb {
 
 constexpr static const char *const TAG = "display.mipi_rgb";
 const uint8_t SW_RESET_CMD = 0x01;
@@ -120,6 +119,5 @@ class MipiRgbSpi : public MipiRgb,
 };
 #endif
 
-}  // namespace mipi_rgb
-}  // namespace esphome
+}  // namespace esphome::mipi_rgb
 #endif
diff --git a/esphome/components/neopixelbus/neopixelbus_light.h b/esphome/components/neopixelbus/neopixelbus_light.h
index c27244b94dd..1cbe889acf9 100644
--- a/esphome/components/neopixelbus/neopixelbus_light.h
+++ b/esphome/components/neopixelbus/neopixelbus_light.h
@@ -11,8 +11,7 @@
 
 #include "NeoPixelBus.h"
 
-namespace esphome {
-namespace neopixelbus {
+namespace esphome::neopixelbus {
 
 enum class ESPNeoPixelOrder {
   GBWR = 0b11000110,
@@ -140,7 +139,6 @@ class NeoPixelRGBWLightOutput : public NeoPixelBusLightOutputBase<T_METHOD, T_CO
   }
 };
 
-}  // namespace neopixelbus
-}  // namespace esphome
+}  // namespace esphome::neopixelbus
 
 #endif  // USE_ARDUINO
diff --git a/esphome/components/qspi_dbi/qspi_dbi.cpp b/esphome/components/qspi_dbi/qspi_dbi.cpp
index d42f95dca37..5b4974b6317 100644
--- a/esphome/components/qspi_dbi/qspi_dbi.cpp
+++ b/esphome/components/qspi_dbi/qspi_dbi.cpp
@@ -3,8 +3,7 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace qspi_dbi {
+namespace esphome::qspi_dbi {
 
 // Maximum bytes to log in verbose hex output
 static constexpr size_t QSPI_DBI_MAX_LOG_BYTES = 64;
@@ -226,6 +225,5 @@ void QspiDbi::dump_config() {
   LOG_PIN("  Reset Pin: ", this->reset_pin_);
 }
 
-}  // namespace qspi_dbi
-}  // namespace esphome
+}  // namespace esphome::qspi_dbi
 #endif
diff --git a/esphome/components/qspi_dbi/qspi_dbi.h b/esphome/components/qspi_dbi/qspi_dbi.h
index 3eee9bec47b..fa77cc5f762 100644
--- a/esphome/components/qspi_dbi/qspi_dbi.h
+++ b/esphome/components/qspi_dbi/qspi_dbi.h
@@ -11,8 +11,7 @@
 
 #include "esp_lcd_panel_rgb.h"
 
-namespace esphome {
-namespace qspi_dbi {
+namespace esphome::qspi_dbi {
 
 constexpr static const char *const TAG = "display.qspi_dbi";
 static const uint8_t SW_RESET_CMD = 0x01;
@@ -168,6 +167,5 @@ class QspiDbi : public display::DisplayBuffer,
   esp_lcd_panel_handle_t handle_{};
 };
 
-}  // namespace qspi_dbi
-}  // namespace esphome
+}  // namespace esphome::qspi_dbi
 #endif
diff --git a/esphome/components/rp2040/core.h b/esphome/components/rp2040/core.h
index 92fc4f824e6..db8937a8a36 100644
--- a/esphome/components/rp2040/core.h
+++ b/esphome/components/rp2040/core.h
@@ -7,8 +7,6 @@
 
 extern "C" unsigned long ulMainGetRunTimeCounterValue();
 
-namespace esphome {
-namespace rp2040 {}  // namespace rp2040
-}  // namespace esphome
+namespace esphome::rp2040 {}  // namespace esphome::rp2040
 
 #endif  // USE_RP2040
diff --git a/esphome/components/rp2040/gpio.h b/esphome/components/rp2040/gpio.h
index a98e1dab140..da97cff9b1e 100644
--- a/esphome/components/rp2040/gpio.h
+++ b/esphome/components/rp2040/gpio.h
@@ -5,8 +5,7 @@
 #include <Arduino.h>
 #include "esphome/core/hal.h"
 
-namespace esphome {
-namespace rp2040 {
+namespace esphome::rp2040 {
 
 class RP2040GPIOPin : public InternalGPIOPin {
  public:
@@ -33,7 +32,6 @@ class RP2040GPIOPin : public InternalGPIOPin {
   gpio::Flags flags_{};
 };
 
-}  // namespace rp2040
-}  // namespace esphome
+}  // namespace esphome::rp2040
 
 #endif  // USE_RP2040
diff --git a/esphome/components/rp2040_pio_led_strip/led_strip.cpp b/esphome/components/rp2040_pio_led_strip/led_strip.cpp
index fdb49fb3efe..8afba6ba1d4 100644
--- a/esphome/components/rp2040_pio_led_strip/led_strip.cpp
+++ b/esphome/components/rp2040_pio_led_strip/led_strip.cpp
@@ -12,8 +12,7 @@
 #include <pico/sem.h>
 #include <pico/stdlib.h>
 
-namespace esphome {
-namespace rp2040_pio_led_strip {
+namespace esphome::rp2040_pio_led_strip {
 
 static const char *TAG = "rp2040_pio_led_strip";
 
@@ -210,7 +209,6 @@ void RP2040PIOLEDStripLightOutput::dump_config() {
 
 float RP2040PIOLEDStripLightOutput::get_setup_priority() const { return setup_priority::HARDWARE; }
 
-}  // namespace rp2040_pio_led_strip
-}  // namespace esphome
+}  // namespace esphome::rp2040_pio_led_strip
 
 #endif
diff --git a/esphome/components/rp2040_pio_led_strip/led_strip.h b/esphome/components/rp2040_pio_led_strip/led_strip.h
index 7b626489743..ebc3bbbaa54 100644
--- a/esphome/components/rp2040_pio_led_strip/led_strip.h
+++ b/esphome/components/rp2040_pio_led_strip/led_strip.h
@@ -16,8 +16,7 @@
 #include <pico/sem.h>
 #include <map>
 
-namespace esphome {
-namespace rp2040_pio_led_strip {
+namespace esphome::rp2040_pio_led_strip {
 
 enum RGBOrder : uint8_t {
   ORDER_RGB,
@@ -127,7 +126,6 @@ class RP2040PIOLEDStripLightOutput : public light::AddressableLight {
   inline static struct semaphore dma_write_complete_sem_[12];
 };
 
-}  // namespace rp2040_pio_led_strip
-}  // namespace esphome
+}  // namespace esphome::rp2040_pio_led_strip
 
 #endif  // USE_RP2040
diff --git a/esphome/components/rp2040_pwm/rp2040_pwm.cpp b/esphome/components/rp2040_pwm/rp2040_pwm.cpp
index 90a507b14f7..c9b9e6739d1 100644
--- a/esphome/components/rp2040_pwm/rp2040_pwm.cpp
+++ b/esphome/components/rp2040_pwm/rp2040_pwm.cpp
@@ -11,8 +11,7 @@
 #include <hardware/pwm.h>
 #include <cmath>
 
-namespace esphome {
-namespace rp2040_pwm {
+namespace esphome::rp2040_pwm {
 
 static const char *const TAG = "rp2040_pwm";
 
@@ -60,7 +59,6 @@ void HOT RP2040PWM::write_state(float state) {
   pwm_set_gpio_level(this->pin_->get_pin(), state * this->wrap_);
 }
 
-}  // namespace rp2040_pwm
-}  // namespace esphome
+}  // namespace esphome::rp2040_pwm
 
 #endif
diff --git a/esphome/components/rp2040_pwm/rp2040_pwm.h b/esphome/components/rp2040_pwm/rp2040_pwm.h
index b82765b1c01..58d3955a31e 100644
--- a/esphome/components/rp2040_pwm/rp2040_pwm.h
+++ b/esphome/components/rp2040_pwm/rp2040_pwm.h
@@ -7,8 +7,7 @@
 #include "esphome/core/component.h"
 #include "esphome/core/hal.h"
 
-namespace esphome {
-namespace rp2040_pwm {
+namespace esphome::rp2040_pwm {
 
 class RP2040PWM : public output::FloatOutput, public Component {
  public:
@@ -53,7 +52,6 @@ template<typename... Ts> class SetFrequencyAction : public Action<Ts...> {
   RP2040PWM *parent_;
 };
 
-}  // namespace rp2040_pwm
-}  // namespace esphome
+}  // namespace esphome::rp2040_pwm
 
 #endif  // USE_RP2040
diff --git a/esphome/components/rpi_dpi_rgb/rpi_dpi_rgb.cpp b/esphome/components/rpi_dpi_rgb/rpi_dpi_rgb.cpp
index d29f6a0bcb9..00530c3f96e 100644
--- a/esphome/components/rpi_dpi_rgb/rpi_dpi_rgb.cpp
+++ b/esphome/components/rpi_dpi_rgb/rpi_dpi_rgb.cpp
@@ -4,8 +4,7 @@
 #include "esphome/core/log.h"
 #include <driver/gpio.h>
 
-namespace esphome {
-namespace rpi_dpi_rgb {
+namespace esphome::rpi_dpi_rgb {
 
 void RpiDpiRgb::setup() {
   this->reset_display_();
@@ -160,7 +159,6 @@ void RpiDpiRgb::reset_display_() const {
   }
 }
 
-}  // namespace rpi_dpi_rgb
-}  // namespace esphome
+}  // namespace esphome::rpi_dpi_rgb
 
 #endif  // USE_ESP32_VARIANT_ESP32S3
diff --git a/esphome/components/rpi_dpi_rgb/rpi_dpi_rgb.h b/esphome/components/rpi_dpi_rgb/rpi_dpi_rgb.h
index 7525040cd1f..8b1457926c1 100644
--- a/esphome/components/rpi_dpi_rgb/rpi_dpi_rgb.h
+++ b/esphome/components/rpi_dpi_rgb/rpi_dpi_rgb.h
@@ -14,8 +14,7 @@
 
 #include "esp_lcd_panel_rgb.h"
 
-namespace esphome {
-namespace rpi_dpi_rgb {
+namespace esphome::rpi_dpi_rgb {
 
 constexpr static const char *const TAG = "rpi_dpi_rgb";
 
@@ -92,6 +91,5 @@ class RpiDpiRgb : public display::Display {
   esp_lcd_panel_handle_t handle_{};
 };
 
-}  // namespace rpi_dpi_rgb
-}  // namespace esphome
+}  // namespace esphome::rpi_dpi_rgb
 #endif  // USE_ESP32_VARIANT_ESP32S3
diff --git a/esphome/components/sdl/sdl_esphome.cpp b/esphome/components/sdl/sdl_esphome.cpp
index 74ca2ce39a5..c99b5081b3d 100644
--- a/esphome/components/sdl/sdl_esphome.cpp
+++ b/esphome/components/sdl/sdl_esphome.cpp
@@ -2,8 +2,7 @@
 #include "sdl_esphome.h"
 #include "esphome/components/display/display_color_utils.h"
 
-namespace esphome {
-namespace sdl {
+namespace esphome::sdl {
 
 int Sdl::get_width() {
   switch (this->rotation_) {
@@ -162,6 +161,5 @@ void Sdl::loop() {
   }
 }
 
-}  // namespace sdl
-}  // namespace esphome
+}  // namespace esphome::sdl
 #endif
diff --git a/esphome/components/sdl/sdl_esphome.h b/esphome/components/sdl/sdl_esphome.h
index ce34cb817e0..3f54b705606 100644
--- a/esphome/components/sdl/sdl_esphome.h
+++ b/esphome/components/sdl/sdl_esphome.h
@@ -9,8 +9,7 @@
 #include "SDL.h"
 #include <map>
 
-namespace esphome {
-namespace sdl {
+namespace esphome::sdl {
 
 constexpr static const char *const TAG = "sdl";
 
@@ -66,7 +65,6 @@ class Sdl : public display::Display {
   uint16_t y_high_{0};
   std::map<int32_t, CallbackManager<void(bool)>> key_callbacks_{};
 };
-}  // namespace sdl
-}  // namespace esphome
+}  // namespace esphome::sdl
 
 #endif
diff --git a/esphome/components/sdl/touchscreen/sdl_touchscreen.h b/esphome/components/sdl/touchscreen/sdl_touchscreen.h
index a1f0fb15e32..cf2fd650889 100644
--- a/esphome/components/sdl/touchscreen/sdl_touchscreen.h
+++ b/esphome/components/sdl/touchscreen/sdl_touchscreen.h
@@ -4,8 +4,7 @@
 #include "../sdl_esphome.h"
 #include "esphome/components/touchscreen/touchscreen.h"
 
-namespace esphome {
-namespace sdl {
+namespace esphome::sdl {
 
 class SdlTouchscreen : public touchscreen::Touchscreen, public Parented<Sdl> {
  public:
@@ -21,6 +20,5 @@ class SdlTouchscreen : public touchscreen::Touchscreen, public Parented<Sdl> {
   }
 };
 
-}  // namespace sdl
-}  // namespace esphome
+}  // namespace esphome::sdl
 #endif
diff --git a/esphome/components/shelly_dimmer/dev_table.h b/esphome/components/shelly_dimmer/dev_table.h
index e73cd1271cb..32b4810d7a2 100644
--- a/esphome/components/shelly_dimmer/dev_table.h
+++ b/esphome/components/shelly_dimmer/dev_table.h
@@ -23,8 +23,7 @@
 #ifdef USE_SHD_FIRMWARE_DATA
 #include "stm32flash.h"
 
-namespace esphome {
-namespace shelly_dimmer {
+namespace esphome::shelly_dimmer {
 
 constexpr uint32_t SZ_128 = 0x00000080;
 constexpr uint32_t SZ_256 = 0x00000100;
@@ -153,7 +152,6 @@ constexpr stm32_dev_t DEVICES[] = {
     {0x0, "", 0x0, 0x0, 0x0, 0x0, 0x0, nullptr, 0x0, 0x0, 0x0, 0x0, 0x0},
 };
 
-}  // namespace shelly_dimmer
-}  // namespace esphome
+}  // namespace esphome::shelly_dimmer
 
 #endif  // USE_SHD_FIRMWARE_DATA
diff --git a/esphome/components/shelly_dimmer/shelly_dimmer.cpp b/esphome/components/shelly_dimmer/shelly_dimmer.cpp
index 230fb963b13..b0f43f0ffca 100644
--- a/esphome/components/shelly_dimmer/shelly_dimmer.cpp
+++ b/esphome/components/shelly_dimmer/shelly_dimmer.cpp
@@ -56,8 +56,7 @@ template<typename T, size_t N> constexpr size_t size(const T (&/*unused*/)[N]) n
 
 }  // Anonymous namespace
 
-namespace esphome {
-namespace shelly_dimmer {
+namespace esphome::shelly_dimmer {
 
 /// Computes a crappy checksum as defined by the Shelly Dimmer protocol.
 uint16_t shelly_dimmer_checksum(const uint8_t *buf, int len) {
@@ -522,7 +521,6 @@ void ShellyDimmer::reset_dfu_boot_() {
   this->reset_(true);
 }
 
-}  // namespace shelly_dimmer
-}  // namespace esphome
+}  // namespace esphome::shelly_dimmer
 
 #endif  // USE_ESP8266
diff --git a/esphome/components/shelly_dimmer/shelly_dimmer.h b/esphome/components/shelly_dimmer/shelly_dimmer.h
index fd75caa797d..c6d0e20afe8 100644
--- a/esphome/components/shelly_dimmer/shelly_dimmer.h
+++ b/esphome/components/shelly_dimmer/shelly_dimmer.h
@@ -10,8 +10,7 @@
 
 #include <array>
 
-namespace esphome {
-namespace shelly_dimmer {
+namespace esphome::shelly_dimmer {
 
 class ShellyDimmer : public PollingComponent, public light::LightOutput, public uart::UARTDevice {
  private:
@@ -117,7 +116,6 @@ class ShellyDimmer : public PollingComponent, public light::LightOutput, public
   void reset_dfu_boot_();
 };
 
-}  // namespace shelly_dimmer
-}  // namespace esphome
+}  // namespace esphome::shelly_dimmer
 
 #endif  // USE_ESP8266
diff --git a/esphome/components/shelly_dimmer/stm32flash.cpp b/esphome/components/shelly_dimmer/stm32flash.cpp
index a1a933bcab1..c758b0a3123 100644
--- a/esphome/components/shelly_dimmer/stm32flash.cpp
+++ b/esphome/components/shelly_dimmer/stm32flash.cpp
@@ -112,8 +112,7 @@ constexpr char TAG[] = "stm32flash";
 
 }  // Anonymous namespace
 
-namespace esphome {
-namespace shelly_dimmer {
+namespace esphome::shelly_dimmer {
 
 namespace {
 
@@ -487,12 +486,6 @@ template<typename T> stm32_unique_ptr make_stm32_with_deletor(T ptr) {
 
 }  // Anonymous namespace
 
-}  // namespace shelly_dimmer
-}  // namespace esphome
-
-namespace esphome {
-namespace shelly_dimmer {
-
 /* find newer command by higher code */
 #define newer(prev, a) (((prev) == STM32_CMD_ERR) ? (a) : (((prev) > (a)) ? (prev) : (a)))
 
@@ -1059,7 +1052,6 @@ stm32_err_t stm32_crc_wrapper(const stm32_unique_ptr &stm, uint32_t address, uin
   return STM32_ERR_OK;
 }
 
-}  // namespace shelly_dimmer
-}  // namespace esphome
+}  // namespace esphome::shelly_dimmer
 
 #endif  // USE_SHD_FIRMWARE_DATA
diff --git a/esphome/components/shelly_dimmer/stm32flash.h b/esphome/components/shelly_dimmer/stm32flash.h
index d973b352221..9a81f07373e 100644
--- a/esphome/components/shelly_dimmer/stm32flash.h
+++ b/esphome/components/shelly_dimmer/stm32flash.h
@@ -26,8 +26,7 @@
 #include <memory>
 #include "esphome/components/uart/uart.h"
 
-namespace esphome {
-namespace shelly_dimmer {
+namespace esphome::shelly_dimmer {
 
 /* flags */
 constexpr auto STREAM_OPT_BYTE = (1 << 0);      /* byte (not frame) oriented */
@@ -125,7 +124,6 @@ stm32_err_t stm32_crc_memory(const stm32_unique_ptr &stm, uint32_t address, uint
 stm32_err_t stm32_crc_wrapper(const stm32_unique_ptr &stm, uint32_t address, uint32_t length, uint32_t *crc);
 uint32_t stm32_sw_crc(uint32_t crc, uint8_t *buf, unsigned int len);
 
-}  // namespace shelly_dimmer
-}  // namespace esphome
+}  // namespace esphome::shelly_dimmer
 
 #endif  // USE_SHD_FIRMWARE_DATA
diff --git a/esphome/components/st7701s/st7701s.cpp b/esphome/components/st7701s/st7701s.cpp
index 701b6dd79ea..dac8ac9dbcd 100644
--- a/esphome/components/st7701s/st7701s.cpp
+++ b/esphome/components/st7701s/st7701s.cpp
@@ -4,8 +4,7 @@
 #include "esphome/core/log.h"
 #include <driver/gpio.h>
 
-namespace esphome {
-namespace st7701s {
+namespace esphome::st7701s {
 
 void ST7701S::setup() {
   this->spi_setup();
@@ -195,6 +194,5 @@ void ST7701S::dump_config() {
   ESP_LOGCONFIG(TAG, "  SPI Data rate: %dMHz", (unsigned) (this->data_rate_ / 1000000));
 }
 
-}  // namespace st7701s
-}  // namespace esphome
+}  // namespace esphome::st7701s
 #endif  // USE_ESP32_VARIANT_ESP32S3
diff --git a/esphome/components/st7701s/st7701s.h b/esphome/components/st7701s/st7701s.h
index a1e3c2e54a0..de5e4c13d49 100644
--- a/esphome/components/st7701s/st7701s.h
+++ b/esphome/components/st7701s/st7701s.h
@@ -12,8 +12,7 @@
 
 #include "esp_lcd_panel_rgb.h"
 
-namespace esphome {
-namespace st7701s {
+namespace esphome::st7701s {
 
 constexpr static const char *const TAG = "display.st7701s";
 const uint8_t SW_RESET_CMD = 0x01;
@@ -113,6 +112,5 @@ class ST7701S : public display::Display,
   esp_lcd_panel_handle_t handle_{};
 };
 
-}  // namespace st7701s
-}  // namespace esphome
+}  // namespace esphome::st7701s
 #endif
diff --git a/tests/integration/fixtures/external_components/crc8_test_component/crc8_test_component.cpp b/tests/integration/fixtures/external_components/crc8_test_component/crc8_test_component.cpp
index 6c46af19fdf..0c0201508af 100644
--- a/tests/integration/fixtures/external_components/crc8_test_component/crc8_test_component.cpp
+++ b/tests/integration/fixtures/external_components/crc8_test_component/crc8_test_component.cpp
@@ -2,8 +2,7 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace crc8_test_component {
+namespace esphome::crc8_test_component {
 
 static const char *const TAG = "crc8_test";
 
@@ -166,5 +165,4 @@ void CRC8TestComponent::log_test_result(const char *test_name, bool passed) {
   }
 }
 
-}  // namespace crc8_test_component
-}  // namespace esphome
+}  // namespace esphome::crc8_test_component
diff --git a/tests/integration/fixtures/external_components/crc8_test_component/crc8_test_component.h b/tests/integration/fixtures/external_components/crc8_test_component/crc8_test_component.h
index 3b8847259c3..5d21ab134e0 100644
--- a/tests/integration/fixtures/external_components/crc8_test_component/crc8_test_component.h
+++ b/tests/integration/fixtures/external_components/crc8_test_component/crc8_test_component.h
@@ -4,8 +4,7 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace crc8_test_component {
+namespace esphome::crc8_test_component {
 
 class CRC8TestComponent : public Component {
  public:
@@ -25,5 +24,4 @@ class CRC8TestComponent : public Component {
                    uint8_t poly = 0x8C, bool msb_first = false);
 };
 
-}  // namespace crc8_test_component
-}  // namespace esphome
+}  // namespace esphome::crc8_test_component
diff --git a/tests/integration/fixtures/external_components/custom_api_device_component/custom_api_device_component.cpp b/tests/integration/fixtures/external_components/custom_api_device_component/custom_api_device_component.cpp
index c86ab992425..b66372d8ba6 100644
--- a/tests/integration/fixtures/external_components/custom_api_device_component/custom_api_device_component.cpp
+++ b/tests/integration/fixtures/external_components/custom_api_device_component/custom_api_device_component.cpp
@@ -2,8 +2,7 @@
 #include "esphome/core/log.h"
 
 #ifdef USE_API
-namespace esphome {
-namespace custom_api_device_component {
+namespace esphome::custom_api_device_component {
 
 static const char *const TAG = "custom_api";
 
@@ -58,6 +57,5 @@ void CustomAPIDeviceComponent::on_ha_state_changed(std::string entity_id, std::s
   ESP_LOGI(TAG, "This subscription uses std::string API for backward compatibility");
 }
 
-}  // namespace custom_api_device_component
-}  // namespace esphome
+}  // namespace esphome::custom_api_device_component
 #endif  // USE_API
diff --git a/tests/integration/fixtures/external_components/custom_api_device_component/custom_api_device_component.h b/tests/integration/fixtures/external_components/custom_api_device_component/custom_api_device_component.h
index 4d519d3ed1f..e75b3401223 100644
--- a/tests/integration/fixtures/external_components/custom_api_device_component/custom_api_device_component.h
+++ b/tests/integration/fixtures/external_components/custom_api_device_component/custom_api_device_component.h
@@ -6,8 +6,7 @@
 #include "esphome/components/api/custom_api_device.h"
 
 #ifdef USE_API
-namespace esphome {
-namespace custom_api_device_component {
+namespace esphome::custom_api_device_component {
 
 using namespace api;
 
@@ -28,6 +27,5 @@ class CustomAPIDeviceComponent : public Component, public CustomAPIDevice {
   void on_ha_state_changed(std::string entity_id, std::string state);
 };
 
-}  // namespace custom_api_device_component
-}  // namespace esphome
+}  // namespace esphome::custom_api_device_component
 #endif  // USE_API
diff --git a/tests/integration/fixtures/external_components/defer_stress_component/defer_stress_component.cpp b/tests/integration/fixtures/external_components/defer_stress_component/defer_stress_component.cpp
index 21ca45947ec..5c3bbeea84d 100644
--- a/tests/integration/fixtures/external_components/defer_stress_component/defer_stress_component.cpp
+++ b/tests/integration/fixtures/external_components/defer_stress_component/defer_stress_component.cpp
@@ -5,8 +5,7 @@
 #include <vector>
 #include <chrono>
 
-namespace esphome {
-namespace defer_stress_component {
+namespace esphome::defer_stress_component {
 
 static const char *const TAG = "defer_stress";
 
@@ -71,5 +70,4 @@ void DeferStressComponent::run_multi_thread_test() {
   ESP_LOGI(TAG, "All threads finished in %lldms. Created %d defer requests", thread_time, this->total_defers_.load());
 }
 
-}  // namespace defer_stress_component
-}  // namespace esphome
+}  // namespace esphome::defer_stress_component
diff --git a/tests/integration/fixtures/external_components/defer_stress_component/defer_stress_component.h b/tests/integration/fixtures/external_components/defer_stress_component/defer_stress_component.h
index 59b75657260..2aac0aeddce 100644
--- a/tests/integration/fixtures/external_components/defer_stress_component/defer_stress_component.h
+++ b/tests/integration/fixtures/external_components/defer_stress_component/defer_stress_component.h
@@ -3,8 +3,7 @@
 #include "esphome/core/component.h"
 #include <atomic>
 
-namespace esphome {
-namespace defer_stress_component {
+namespace esphome::defer_stress_component {
 
 class DeferStressComponent : public Component {
  public:
@@ -16,5 +15,4 @@ class DeferStressComponent : public Component {
   std::atomic<int> executed_defers_{0};
 };
 
-}  // namespace defer_stress_component
-}  // namespace esphome
+}  // namespace esphome::defer_stress_component
diff --git a/tests/integration/fixtures/external_components/loop_test_component/loop_test_component.cpp b/tests/integration/fixtures/external_components/loop_test_component/loop_test_component.cpp
index 28a05d3d45d..dd54381c350 100644
--- a/tests/integration/fixtures/external_components/loop_test_component/loop_test_component.cpp
+++ b/tests/integration/fixtures/external_components/loop_test_component/loop_test_component.cpp
@@ -1,7 +1,6 @@
 #include "loop_test_component.h"
 
-namespace esphome {
-namespace loop_test_component {
+namespace esphome::loop_test_component {
 
 void LoopTestComponent::setup() { ESP_LOGI(TAG, "[%s] Setup called", this->name_.c_str()); }
 
@@ -63,5 +62,4 @@ void LoopTestUpdateComponent::update() {
            this->update_count_, loop_disabled ? "YES" : "NO");
 }
 
-}  // namespace loop_test_component
-}  // namespace esphome
+}  // namespace esphome::loop_test_component
diff --git a/tests/integration/fixtures/external_components/loop_test_component/loop_test_component.h b/tests/integration/fixtures/external_components/loop_test_component/loop_test_component.h
index 3dca2da2e9f..1a814118619 100644
--- a/tests/integration/fixtures/external_components/loop_test_component/loop_test_component.h
+++ b/tests/integration/fixtures/external_components/loop_test_component/loop_test_component.h
@@ -6,8 +6,7 @@
 #include "esphome/core/automation.h"
 #include "esphome/core/helpers.h"
 
-namespace esphome {
-namespace loop_test_component {
+namespace esphome::loop_test_component {
 
 static const char *const TAG = "loop_test_component";
 
@@ -79,5 +78,4 @@ class LoopTestUpdateComponent : public PollingComponent {
   int disable_loop_after_{0};
 };
 
-}  // namespace loop_test_component
-}  // namespace esphome
+}  // namespace esphome::loop_test_component
diff --git a/tests/integration/fixtures/external_components/loop_test_component/loop_test_isr_component.cpp b/tests/integration/fixtures/external_components/loop_test_component/loop_test_isr_component.cpp
index 30afec04223..b6f94aacf2d 100644
--- a/tests/integration/fixtures/external_components/loop_test_component/loop_test_isr_component.cpp
+++ b/tests/integration/fixtures/external_components/loop_test_component/loop_test_isr_component.cpp
@@ -2,8 +2,7 @@
 #include "esphome/core/hal.h"
 #include "esphome/core/application.h"
 
-namespace esphome {
-namespace loop_test_component {
+namespace esphome::loop_test_component {
 
 static const char *const ISR_TAG = "loop_test_isr_component";
 
@@ -76,5 +75,4 @@ void IRAM_ATTR LoopTestISRComponent::simulate_isr_enable() {
   // For testing, we'll track the call count and log it from the main loop
 }
 
-}  // namespace loop_test_component
-}  // namespace esphome
+}  // namespace esphome::loop_test_component
diff --git a/tests/integration/fixtures/external_components/loop_test_component/loop_test_isr_component.h b/tests/integration/fixtures/external_components/loop_test_component/loop_test_isr_component.h
index 20e11b5ecdb..5537bd02333 100644
--- a/tests/integration/fixtures/external_components/loop_test_component/loop_test_isr_component.h
+++ b/tests/integration/fixtures/external_components/loop_test_component/loop_test_isr_component.h
@@ -4,8 +4,7 @@
 #include "esphome/core/log.h"
 #include "esphome/core/hal.h"
 
-namespace esphome {
-namespace loop_test_component {
+namespace esphome::loop_test_component {
 
 class LoopTestISRComponent : public Component {
  public:
@@ -28,5 +27,4 @@ class LoopTestISRComponent : public Component {
   int isr_call_count_{0};
 };
 
-}  // namespace loop_test_component
-}  // namespace esphome
+}  // namespace esphome::loop_test_component
diff --git a/tests/integration/fixtures/external_components/scheduler_bulk_cleanup_component/scheduler_bulk_cleanup_component.cpp b/tests/integration/fixtures/external_components/scheduler_bulk_cleanup_component/scheduler_bulk_cleanup_component.cpp
index be85228c3cf..f6fd1b1de72 100644
--- a/tests/integration/fixtures/external_components/scheduler_bulk_cleanup_component/scheduler_bulk_cleanup_component.cpp
+++ b/tests/integration/fixtures/external_components/scheduler_bulk_cleanup_component/scheduler_bulk_cleanup_component.cpp
@@ -2,8 +2,7 @@
 #include "esphome/core/log.h"
 #include "esphome/core/helpers.h"
 
-namespace esphome {
-namespace scheduler_bulk_cleanup_component {
+namespace esphome::scheduler_bulk_cleanup_component {
 
 static const char *const TAG = "bulk_cleanup";
 
@@ -68,5 +67,4 @@ void SchedulerBulkCleanupComponent::trigger_bulk_cleanup() {
   }
 }
 
-}  // namespace scheduler_bulk_cleanup_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_bulk_cleanup_component
diff --git a/tests/integration/fixtures/external_components/scheduler_bulk_cleanup_component/scheduler_bulk_cleanup_component.h b/tests/integration/fixtures/external_components/scheduler_bulk_cleanup_component/scheduler_bulk_cleanup_component.h
index f55472d426c..34b4a8e0d01 100644
--- a/tests/integration/fixtures/external_components/scheduler_bulk_cleanup_component/scheduler_bulk_cleanup_component.h
+++ b/tests/integration/fixtures/external_components/scheduler_bulk_cleanup_component/scheduler_bulk_cleanup_component.h
@@ -3,8 +3,7 @@
 #include "esphome/core/component.h"
 #include "esphome/core/application.h"
 
-namespace esphome {
-namespace scheduler_bulk_cleanup_component {
+namespace esphome::scheduler_bulk_cleanup_component {
 
 class SchedulerBulkCleanupComponent : public Component {
  public:
@@ -14,5 +13,4 @@ class SchedulerBulkCleanupComponent : public Component {
   void trigger_bulk_cleanup();
 };
 
-}  // namespace scheduler_bulk_cleanup_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_bulk_cleanup_component
diff --git a/tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.cpp b/tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.cpp
index 305d3595919..f75a2fdd920 100644
--- a/tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.cpp
+++ b/tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.cpp
@@ -6,8 +6,7 @@
 #include <chrono>
 #include <random>
 
-namespace esphome {
-namespace scheduler_heap_stress_component {
+namespace esphome::scheduler_heap_stress_component {
 
 static const char *const TAG = "scheduler_heap_stress";
 
@@ -100,5 +99,4 @@ void SchedulerHeapStressComponent::run_multi_thread_test() {
   ESP_LOGI(TAG, "All threads finished in %lldms. Created %d callbacks", thread_time, this->total_callbacks_.load());
 }
 
-}  // namespace scheduler_heap_stress_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_heap_stress_component
diff --git a/tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.h b/tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.h
index 5da32ca9f8a..9f7810d0adf 100644
--- a/tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.h
+++ b/tests/integration/fixtures/external_components/scheduler_heap_stress_component/heap_scheduler_stress_component.h
@@ -3,8 +3,7 @@
 #include "esphome/core/component.h"
 #include <atomic>
 
-namespace esphome {
-namespace scheduler_heap_stress_component {
+namespace esphome::scheduler_heap_stress_component {
 
 class SchedulerHeapStressComponent : public Component {
  public:
@@ -18,5 +17,4 @@ class SchedulerHeapStressComponent : public Component {
   std::atomic<int> executed_callbacks_{0};
 };
 
-}  // namespace scheduler_heap_stress_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_heap_stress_component
diff --git a/tests/integration/fixtures/external_components/scheduler_rapid_cancellation_component/rapid_cancellation_component.cpp b/tests/integration/fixtures/external_components/scheduler_rapid_cancellation_component/rapid_cancellation_component.cpp
index b735c453f2d..0e5525d2656 100644
--- a/tests/integration/fixtures/external_components/scheduler_rapid_cancellation_component/rapid_cancellation_component.cpp
+++ b/tests/integration/fixtures/external_components/scheduler_rapid_cancellation_component/rapid_cancellation_component.cpp
@@ -6,8 +6,7 @@
 #include <random>
 #include <sstream>
 
-namespace esphome {
-namespace scheduler_rapid_cancellation_component {
+namespace esphome::scheduler_rapid_cancellation_component {
 
 static const char *const TAG = "scheduler_rapid_cancellation";
 
@@ -76,5 +75,4 @@ void SchedulerRapidCancellationComponent::run_rapid_cancellation_test() {
   });
 }
 
-}  // namespace scheduler_rapid_cancellation_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_rapid_cancellation_component
diff --git a/tests/integration/fixtures/external_components/scheduler_rapid_cancellation_component/rapid_cancellation_component.h b/tests/integration/fixtures/external_components/scheduler_rapid_cancellation_component/rapid_cancellation_component.h
index 0a01b2a8de7..f1ef9a72b61 100644
--- a/tests/integration/fixtures/external_components/scheduler_rapid_cancellation_component/rapid_cancellation_component.h
+++ b/tests/integration/fixtures/external_components/scheduler_rapid_cancellation_component/rapid_cancellation_component.h
@@ -3,8 +3,7 @@
 #include "esphome/core/component.h"
 #include <atomic>
 
-namespace esphome {
-namespace scheduler_rapid_cancellation_component {
+namespace esphome::scheduler_rapid_cancellation_component {
 
 class SchedulerRapidCancellationComponent : public Component {
  public:
@@ -18,5 +17,4 @@ class SchedulerRapidCancellationComponent : public Component {
   std::atomic<int> total_executed_{0};
 };
 
-}  // namespace scheduler_rapid_cancellation_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_rapid_cancellation_component
diff --git a/tests/integration/fixtures/external_components/scheduler_recursive_timeout_component/recursive_timeout_component.cpp b/tests/integration/fixtures/external_components/scheduler_recursive_timeout_component/recursive_timeout_component.cpp
index 2a08bd72a9f..6bc03f34c0d 100644
--- a/tests/integration/fixtures/external_components/scheduler_recursive_timeout_component/recursive_timeout_component.cpp
+++ b/tests/integration/fixtures/external_components/scheduler_recursive_timeout_component/recursive_timeout_component.cpp
@@ -1,8 +1,7 @@
 #include "recursive_timeout_component.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace scheduler_recursive_timeout_component {
+namespace esphome::scheduler_recursive_timeout_component {
 
 static const char *const TAG = "scheduler_recursive_timeout";
 
@@ -36,5 +35,4 @@ void SchedulerRecursiveTimeoutComponent::run_recursive_timeout_test() {
   });
 }
 
-}  // namespace scheduler_recursive_timeout_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_recursive_timeout_component
diff --git a/tests/integration/fixtures/external_components/scheduler_recursive_timeout_component/recursive_timeout_component.h b/tests/integration/fixtures/external_components/scheduler_recursive_timeout_component/recursive_timeout_component.h
index 8d2c085a111..237f9785b21 100644
--- a/tests/integration/fixtures/external_components/scheduler_recursive_timeout_component/recursive_timeout_component.h
+++ b/tests/integration/fixtures/external_components/scheduler_recursive_timeout_component/recursive_timeout_component.h
@@ -2,8 +2,7 @@
 
 #include "esphome/core/component.h"
 
-namespace esphome {
-namespace scheduler_recursive_timeout_component {
+namespace esphome::scheduler_recursive_timeout_component {
 
 class SchedulerRecursiveTimeoutComponent : public Component {
  public:
@@ -16,5 +15,4 @@ class SchedulerRecursiveTimeoutComponent : public Component {
   int nested_level_{0};
 };
 
-}  // namespace scheduler_recursive_timeout_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_recursive_timeout_component
diff --git a/tests/integration/fixtures/external_components/scheduler_simultaneous_callbacks_component/simultaneous_callbacks_component.cpp b/tests/integration/fixtures/external_components/scheduler_simultaneous_callbacks_component/simultaneous_callbacks_component.cpp
index b4c2b8c6c2d..a817b9f508f 100644
--- a/tests/integration/fixtures/external_components/scheduler_simultaneous_callbacks_component/simultaneous_callbacks_component.cpp
+++ b/tests/integration/fixtures/external_components/scheduler_simultaneous_callbacks_component/simultaneous_callbacks_component.cpp
@@ -5,8 +5,7 @@
 #include <chrono>
 #include <sstream>
 
-namespace esphome {
-namespace scheduler_simultaneous_callbacks_component {
+namespace esphome::scheduler_simultaneous_callbacks_component {
 
 static const char *const TAG = "scheduler_simultaneous_callbacks";
 
@@ -105,5 +104,4 @@ void SchedulerSimultaneousCallbacksComponent::run_simultaneous_callbacks_test()
   });
 }
 
-}  // namespace scheduler_simultaneous_callbacks_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_simultaneous_callbacks_component
diff --git a/tests/integration/fixtures/external_components/scheduler_simultaneous_callbacks_component/simultaneous_callbacks_component.h b/tests/integration/fixtures/external_components/scheduler_simultaneous_callbacks_component/simultaneous_callbacks_component.h
index 1a36af4b3de..9746331aec1 100644
--- a/tests/integration/fixtures/external_components/scheduler_simultaneous_callbacks_component/simultaneous_callbacks_component.h
+++ b/tests/integration/fixtures/external_components/scheduler_simultaneous_callbacks_component/simultaneous_callbacks_component.h
@@ -3,8 +3,7 @@
 #include "esphome/core/component.h"
 #include <atomic>
 
-namespace esphome {
-namespace scheduler_simultaneous_callbacks_component {
+namespace esphome::scheduler_simultaneous_callbacks_component {
 
 class SchedulerSimultaneousCallbacksComponent : public Component {
  public:
@@ -20,5 +19,4 @@ class SchedulerSimultaneousCallbacksComponent : public Component {
   std::atomic<int> max_concurrent_{0};
 };
 
-}  // namespace scheduler_simultaneous_callbacks_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_simultaneous_callbacks_component
diff --git a/tests/integration/fixtures/external_components/scheduler_string_lifetime_component/string_lifetime_component.cpp b/tests/integration/fixtures/external_components/scheduler_string_lifetime_component/string_lifetime_component.cpp
index 8c3f665f197..cc1b9f78147 100644
--- a/tests/integration/fixtures/external_components/scheduler_string_lifetime_component/string_lifetime_component.cpp
+++ b/tests/integration/fixtures/external_components/scheduler_string_lifetime_component/string_lifetime_component.cpp
@@ -4,8 +4,7 @@
 #include <thread>
 #include <chrono>
 
-namespace esphome {
-namespace scheduler_string_lifetime_component {
+namespace esphome::scheduler_string_lifetime_component {
 
 static const char *const TAG = "scheduler_string_lifetime";
 
@@ -258,5 +257,4 @@ void SchedulerStringLifetimeComponent::test_lambda_capture_lifetime() {
   });
 }
 
-}  // namespace scheduler_string_lifetime_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_string_lifetime_component
diff --git a/tests/integration/fixtures/external_components/scheduler_string_lifetime_component/string_lifetime_component.h b/tests/integration/fixtures/external_components/scheduler_string_lifetime_component/string_lifetime_component.h
index 95532328bb8..20185f128d1 100644
--- a/tests/integration/fixtures/external_components/scheduler_string_lifetime_component/string_lifetime_component.h
+++ b/tests/integration/fixtures/external_components/scheduler_string_lifetime_component/string_lifetime_component.h
@@ -4,8 +4,7 @@
 #include <vector>
 #include <string>
 
-namespace esphome {
-namespace scheduler_string_lifetime_component {
+namespace esphome::scheduler_string_lifetime_component {
 
 class SchedulerStringLifetimeComponent : public Component {
  public:
@@ -33,5 +32,4 @@ class SchedulerStringLifetimeComponent : public Component {
   int tests_failed_{0};
 };
 
-}  // namespace scheduler_string_lifetime_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_string_lifetime_component
diff --git a/tests/integration/fixtures/external_components/scheduler_string_name_stress_component/string_name_stress_component.cpp b/tests/integration/fixtures/external_components/scheduler_string_name_stress_component/string_name_stress_component.cpp
index 9071e573bbf..677d371f255 100644
--- a/tests/integration/fixtures/external_components/scheduler_string_name_stress_component/string_name_stress_component.cpp
+++ b/tests/integration/fixtures/external_components/scheduler_string_name_stress_component/string_name_stress_component.cpp
@@ -7,8 +7,7 @@
 #include <string>
 #include <sstream>
 
-namespace esphome {
-namespace scheduler_string_name_stress_component {
+namespace esphome::scheduler_string_name_stress_component {
 
 static const char *const TAG = "scheduler_string_name_stress";
 
@@ -106,5 +105,4 @@ void SchedulerStringNameStressComponent::run_string_name_stress_test() {
   });
 }
 
-}  // namespace scheduler_string_name_stress_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_string_name_stress_component
diff --git a/tests/integration/fixtures/external_components/scheduler_string_name_stress_component/string_name_stress_component.h b/tests/integration/fixtures/external_components/scheduler_string_name_stress_component/string_name_stress_component.h
index 002a0a7b511..121bda62041 100644
--- a/tests/integration/fixtures/external_components/scheduler_string_name_stress_component/string_name_stress_component.h
+++ b/tests/integration/fixtures/external_components/scheduler_string_name_stress_component/string_name_stress_component.h
@@ -3,8 +3,7 @@
 #include "esphome/core/component.h"
 #include <atomic>
 
-namespace esphome {
-namespace scheduler_string_name_stress_component {
+namespace esphome::scheduler_string_name_stress_component {
 
 class SchedulerStringNameStressComponent : public Component {
  public:
@@ -18,5 +17,4 @@ class SchedulerStringNameStressComponent : public Component {
   std::atomic<int> executed_callbacks_{0};
 };
 
-}  // namespace scheduler_string_name_stress_component
-}  // namespace esphome
+}  // namespace esphome::scheduler_string_name_stress_component