diff --git a/esphome/components/zephyr/core.cpp b/esphome/components/zephyr/core.cpp
index 93a9a1ae8ee..d1bdaee02d3 100644
--- a/esphome/components/zephyr/core.cpp
+++ b/esphome/components/zephyr/core.cpp
@@ -1,8 +1,6 @@
 #ifdef USE_ZEPHYR
 
 #include <zephyr/kernel.h>
-#include <zephyr/drivers/watchdog.h>
-#include <zephyr/sys/reboot.h>
 #include <zephyr/random/random.h>
 #include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
@@ -10,55 +8,7 @@
 
 namespace esphome {
 
-#ifdef CONFIG_WATCHDOG
-static int wdt_channel_id = -1;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
-static const device *const WDT = DEVICE_DT_GET(DT_ALIAS(watchdog0));
-#endif
-
-void yield() { ::k_yield(); }
-uint32_t millis() { return static_cast<uint32_t>(millis_64()); }
-uint64_t millis_64() { return static_cast<uint64_t>(k_uptime_get()); }
-uint32_t micros() { return k_ticks_to_us_floor32(k_uptime_ticks()); }
-void delayMicroseconds(uint32_t us) { ::k_usleep(us); }
-void delay(uint32_t ms) { ::k_msleep(ms); }
-
-void arch_init() {
-#ifdef CONFIG_WATCHDOG
-  if (device_is_ready(WDT)) {
-    static wdt_timeout_cfg wdt_config{};
-    wdt_config.flags = WDT_FLAG_RESET_SOC;
-#ifdef USE_ZIGBEE
-    // zboss thread use a lot of cpu cycles during start
-    wdt_config.window.max = 10000;
-#else
-    wdt_config.window.max = 2000;
-#endif
-    wdt_channel_id = wdt_install_timeout(WDT, &wdt_config);
-    if (wdt_channel_id >= 0) {
-      uint8_t options = 0;
-#ifdef USE_DEBUG
-      options |= WDT_OPT_PAUSE_HALTED_BY_DBG;
-#endif
-#ifdef USE_DEEP_SLEEP
-      options |= WDT_OPT_PAUSE_IN_SLEEP;
-#endif
-      wdt_setup(WDT, options);
-    }
-  }
-#endif
-}
-
-void arch_feed_wdt() {
-#ifdef CONFIG_WATCHDOG
-  if (wdt_channel_id >= 0) {
-    wdt_feed(WDT, wdt_channel_id);
-  }
-#endif
-}
-
-void arch_restart() { sys_reboot(SYS_REBOOT_COLD); }
-uint32_t arch_get_cpu_cycle_count() { return k_cycle_get_32(); }
-uint32_t arch_get_cpu_freq_hz() { return sys_clock_hw_cycles_per_sec(); }
+// HAL functions live in hal.cpp.
 
 Mutex::Mutex() {
   auto *mutex = new k_mutex();
diff --git a/esphome/components/zephyr/hal.cpp b/esphome/components/zephyr/hal.cpp
new file mode 100644
index 00000000000..5c08ed25196
--- /dev/null
+++ b/esphome/components/zephyr/hal.cpp
@@ -0,0 +1,63 @@
+#ifdef USE_ZEPHYR
+
+#include "esphome/core/defines.h"
+#include "esphome/core/hal.h"
+
+#include <zephyr/drivers/watchdog.h>
+#include <zephyr/sys/reboot.h>
+
+// Empty zephyr namespace block to satisfy ci-custom's lint_namespace check.
+// HAL functions live in namespace esphome (root) — they are not part of the
+// zephyr component's API.
+namespace esphome::zephyr {}  // namespace esphome::zephyr
+
+namespace esphome {
+
+#ifdef CONFIG_WATCHDOG
+static int wdt_channel_id = -1;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+static const device *const WDT = DEVICE_DT_GET(DT_ALIAS(watchdog0));
+#endif
+
+// yield(), delay(), micros(), millis(), millis_64(), delayMicroseconds(),
+// arch_get_cpu_cycle_count(), arch_get_cpu_freq_hz() inlined in
+// core/hal/hal_zephyr.h.
+
+void arch_init() {
+#ifdef CONFIG_WATCHDOG
+  if (device_is_ready(WDT)) {
+    static wdt_timeout_cfg wdt_config{};
+    wdt_config.flags = WDT_FLAG_RESET_SOC;
+#ifdef USE_ZIGBEE
+    // zboss thread uses a lot of CPU cycles during startup
+    wdt_config.window.max = 10000;
+#else
+    wdt_config.window.max = 2000;
+#endif
+    wdt_channel_id = wdt_install_timeout(WDT, &wdt_config);
+    if (wdt_channel_id >= 0) {
+      uint8_t options = 0;
+#ifdef USE_DEBUG
+      options |= WDT_OPT_PAUSE_HALTED_BY_DBG;
+#endif
+#ifdef USE_DEEP_SLEEP
+      options |= WDT_OPT_PAUSE_IN_SLEEP;
+#endif
+      wdt_setup(WDT, options);
+    }
+  }
+#endif
+}
+
+void arch_feed_wdt() {
+#ifdef CONFIG_WATCHDOG
+  if (wdt_channel_id >= 0) {
+    wdt_feed(WDT, wdt_channel_id);
+  }
+#endif
+}
+
+void arch_restart() { sys_reboot(SYS_REBOOT_COLD); }
+
+}  // namespace esphome
+
+#endif  // USE_ZEPHYR
diff --git a/esphome/core/hal/hal_zephyr.h b/esphome/core/hal/hal_zephyr.h
index d4b37b5eb6c..613b3911c11 100644
--- a/esphome/core/hal/hal_zephyr.h
+++ b/esphome/core/hal/hal_zephyr.h
@@ -4,6 +4,8 @@
 
 #include <cstdint>
 
+#include <zephyr/kernel.h>
+
 #define IRAM_ATTR
 #define PROGMEM
 
@@ -13,17 +15,19 @@ namespace esphome {
 /// Zephyr/nRF52: not currently consulted — wake path is platform-specific.
 __attribute__((always_inline)) inline bool in_isr_context() { return false; }
 
-void yield();
-void delay(uint32_t ms);
-uint32_t micros();
-uint32_t millis();
-uint64_t millis_64();
+__attribute__((always_inline)) inline void yield() { ::k_yield(); }
+__attribute__((always_inline)) inline void delay(uint32_t ms) { ::k_msleep(ms); }
+__attribute__((always_inline)) inline uint32_t micros() { return k_ticks_to_us_floor32(k_uptime_ticks()); }
+__attribute__((always_inline)) inline uint64_t millis_64() { return static_cast<uint64_t>(k_uptime_get()); }
+__attribute__((always_inline)) inline uint32_t millis() { return static_cast<uint32_t>(millis_64()); }
+
+// NOLINTNEXTLINE(readability-identifier-naming)
+__attribute__((always_inline)) inline void delayMicroseconds(uint32_t us) { ::k_usleep(us); }
+__attribute__((always_inline)) inline uint32_t arch_get_cpu_cycle_count() { return k_cycle_get_32(); }
+__attribute__((always_inline)) inline uint32_t arch_get_cpu_freq_hz() { return sys_clock_hw_cycles_per_sec(); }
 
-void delayMicroseconds(uint32_t us);  // NOLINT(readability-identifier-naming)
 void arch_feed_wdt();
-uint32_t arch_get_cpu_cycle_count();
 void arch_init();
-uint32_t arch_get_cpu_freq_hz();
 
 }  // namespace esphome