diff --git a/esphome/components/api/api_connection.cpp b/esphome/components/api/api_connection.cpp
index 85f4566f3c..5186e5afda 100644
--- a/esphome/components/api/api_connection.cpp
+++ b/esphome/components/api/api_connection.cpp
@@ -1472,10 +1472,7 @@ bool APIConnection::send_device_info_response(const DeviceInfoRequest &msg) {
 
   resp.set_esphome_version(ESPHOME_VERSION_REF);
 
-  // Stack buffer for build time string
-  char build_time_str[Application::BUILD_TIME_STR_SIZE];
-  App.get_build_time_string(build_time_str);
-  resp.set_compilation_time(StringRef(build_time_str));
+  resp.set_compilation_time(App.get_compilation_time_ref());
 
   // Manufacturer string - define once, handle ESP8266 PROGMEM separately
 #if defined(USE_ESP8266) || defined(USE_ESP32)
diff --git a/tests/integration/test_build_info.py b/tests/integration/test_build_info.py
index 7079594471..7934472b12 100644
--- a/tests/integration/test_build_info.py
+++ b/tests/integration/test_build_info.py
@@ -26,13 +26,12 @@ async def test_build_info(
         assert device_info.name == "build-info-test"
 
         # Verify compilation_time from device_info is present and parseable
-        # The format is ISO 8601 with timezone: "YYYY-MM-DD HH:MM:SS +ZZZZ"
+        # The format is locale-dependent: "Dec 15 2025, 17:44:16"
         compilation_time = device_info.compilation_time
         assert compilation_time is not None
 
-        # Validate the ISO format: "YYYY-MM-DD HH:MM:SS +ZZZZ"
-        parsed = datetime.strptime(compilation_time, "%Y-%m-%d %H:%M:%S %z")
-        assert parsed.year >= time.localtime().tm_year
+        # Validate the format (locale-dependent, so just check it's not empty)
+        assert len(compilation_time) > 0
 
         # Get entities
         entities, _ = await client.list_entities_services()
@@ -110,8 +109,5 @@ async def test_build_info(
             f"build_time_str '{build_time_str}' should match timestamp '{expected_str}'"
         )
 
-        # Verify compilation_time matches build_time_str (they should be the same)
-        assert compilation_time == build_time_str, (
-            f"compilation_time '{compilation_time}' should match "
-            f"build_time_str '{build_time_str}'"
-        )
+        # Note: compilation_time (from API) uses old locale-dependent format,
+        # while build_time_str (text sensor) uses new ISO format