diff --git a/esphome/core/config.py b/esphome/core/config.py
index 3a238e0453..1f40d1608e 100644
--- a/esphome/core/config.py
+++ b/esphome/core/config.py
@@ -495,7 +495,9 @@ async def to_code(config: ConfigType) -> None:
         else:
             # Old way: string-based area (deprecated)
             area_slug = slugify(area_conf)
-            area_id: core.ID = cv.declare_id(Area)
+            area_id = core.ID(
+                cv.validate_id_name(area_slug), is_declaration=True, type=Area
+            )
             area_id_str = area_slug
             _LOGGER.warning(
                 "Using 'area' as a string is deprecated. Please use the new format:\n"
@@ -506,7 +508,7 @@ async def to_code(config: ConfigType) -> None:
                 area_conf,
             )
             # Create a synthetic area for backwards compatibility
-            area_var = cg.Pvariable(area_id)
+            area_var = cg.new_Pvariable(area_id)
             area_id_hash = fnv1a_32bit_hash(area_conf)
             area_name = area_conf
 
diff --git a/tests/integration/fixtures/legacy_area.yaml b/tests/integration/fixtures/legacy_area.yaml
new file mode 100644
index 0000000000..4d1617c395
--- /dev/null
+++ b/tests/integration/fixtures/legacy_area.yaml
@@ -0,0 +1,15 @@
+esphome:
+  name: legacy-area-test
+  # Using legacy string-based area configuration
+  area: Master Bedroom
+
+host:
+api:
+logger:
+
+# Simple sensor to ensure the device compiles and runs
+sensor:
+  - platform: template
+    name: Test Sensor
+    lambda: return 42.0;
+    update_interval: 1s
diff --git a/tests/integration/test_legacy_area.py b/tests/integration/test_legacy_area.py
new file mode 100644
index 0000000000..d10a01ec6a
--- /dev/null
+++ b/tests/integration/test_legacy_area.py
@@ -0,0 +1,41 @@
+"""Integration test for legacy string-based area configuration."""
+
+from __future__ import annotations
+
+import pytest
+
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+
+@pytest.mark.asyncio
+async def test_legacy_area(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test legacy string-based area configuration."""
+    async with run_compiled(yaml_config), api_client_connected() as client:
+        # Get device info which includes areas
+        device_info = await client.device_info()
+        assert device_info is not None
+
+        # Verify the area is reported (should be converted to structured format)
+        areas = device_info.areas
+        assert len(areas) == 1, f"Expected exactly 1 area, got {len(areas)}"
+
+        # Find the area - should be slugified from "Master Bedroom"
+        area = areas[0]
+        assert area.name == "Master Bedroom", (
+            f"Expected area name 'Master Bedroom', got '{area.name}'"
+        )
+
+        # Verify area.id is set (it should be a hash)
+        assert area.area_id > 0, "Area ID should be a positive hash value"
+
+        # The suggested_area field should be set for backward compatibility
+        assert device_info.suggested_area == "Master Bedroom", (
+            f"Expected suggested_area to be 'Master Bedroom', got '{device_info.suggested_area}'"
+        )
+
+        # Verify deprecated warning would have been logged during compilation
+        # (We can't check logs directly in integration tests, but the code should work)