diff --git a/esphome/components/esp32/core.cpp b/esphome/components/esp32/core.cpp
index c97e4a5eb1..0284328ad9 100644
--- a/esphome/components/esp32/core.cpp
+++ b/esphome/components/esp32/core.cpp
@@ -37,6 +37,12 @@ uint32_t IRAM_ATTR HOT millis() {
   return micros_to_millis(static_cast<uint64_t>(esp_timer_get_time()));
 #endif
 }
+// millis_64() stays on esp_timer — a different clock from xTaskGetTickCount(). This is
+// safe because the two are never cross-compared: millis() values are only used for
+// millis()-vs-millis() deltas (feed_wdt, warn_blocking, component start time), while
+// millis_64() is used by the Scheduler and uptime sensors. On ESP32 (USE_NATIVE_64BIT_TIME),
+// Scheduler::millis_64_from_(now) discards the 32-bit now and calls millis_64() directly,
+// so the Scheduler is internally consistent on the esp_timer clock.
 uint64_t HOT millis_64() { return micros_to_millis<uint64_t>(static_cast<uint64_t>(esp_timer_get_time())); }
 void HOT delay(uint32_t ms) { vTaskDelay(ms / portTICK_PERIOD_MS); }
 uint32_t IRAM_ATTR HOT micros() { return (uint32_t) esp_timer_get_time(); }
diff --git a/esphome/core/scheduler.h b/esphome/core/scheduler.h
index 43a3ec7049..5d86736c16 100644
--- a/esphome/core/scheduler.h
+++ b/esphome/core/scheduler.h
@@ -284,8 +284,12 @@ class Scheduler {
   bool cancel_retry_(Component *component, NameType name_type, const char *static_name, uint32_t hash_or_id);
 
   // Extend a 32-bit millis() value to 64-bit. Use when the caller already has a fresh now.
-  // On platforms with native 64-bit time, ignores now and uses millis_64() directly.
-  // On other platforms, extends now to 64-bit using rollover tracking.
+  // On platforms with native 64-bit time (ESP32), ignores now and uses millis_64() directly.
+  // This means the Scheduler uses the esp_timer clock (via millis_64()) for all scheduling,
+  // even though the caller's 32-bit now came from xTaskGetTickCount (via millis()). Safe
+  // because scheduling only compares millis_64 against millis_64 — never against millis().
+  // On other platforms (ESP8266), extends now to 64-bit using rollover tracking, so both
+  // millis() and scheduling use the same clock.
   uint64_t millis_64_from_(uint32_t now) {
 #ifdef USE_NATIVE_64BIT_TIME
     (void) now;