diff --git a/openhands-agent-server/openhands/agent_server/config.py b/openhands-agent-server/openhands/agent_server/config.py
index a277e1e08b..3dbc375ee0 100644
--- a/openhands-agent-server/openhands/agent_server/config.py
+++ b/openhands-agent-server/openhands/agent_server/config.py
@@ -7,6 +7,7 @@
 
 from openhands.agent_server.env_parser import from_env
 from openhands.sdk.utils.cipher import Cipher
+from openhands.sdk.utils.deprecation import warn_deprecated
 
 
 # Environment variable constants
@@ -47,6 +48,24 @@ def _default_secret_key() -> SecretStr | None:
     return None
 
 
+def _default_web_url() -> str | None:
+    web_url = os.getenv("OH_WEB_URL")
+    if web_url:
+        return web_url
+
+    legacy_web_url = os.getenv(V0_RUNTIME_URL)
+    if not legacy_web_url:
+        return None
+
+    warn_deprecated(
+        "RUNTIME_URL environment variable",
+        deprecated_in="1.14.0",
+        removed_in="1.19.0",
+        details="Use OH_WEB_URL instead.",
+    )
+    return legacy_web_url
+
+
 class WebhookSpec(BaseModel):
     """Spec to create a webhook. All webhook requests use POST method."""
 
@@ -165,7 +184,7 @@ class Config(BaseModel):
         ),
     )
     web_url: str | None = Field(
-        default_factory=lambda: os.getenv(V0_RUNTIME_URL),
+        default_factory=_default_web_url,
         description=(
             "The URL where this agent server instance is available externally"
         ),
diff --git a/tests/agent_server/test_api.py b/tests/agent_server/test_api.py
index ca8680d897..22061cd572 100644
--- a/tests/agent_server/test_api.py
+++ b/tests/agent_server/test_api.py
@@ -2,16 +2,24 @@
 
 import asyncio
 import tempfile
+import warnings
 from pathlib import Path
 from unittest.mock import AsyncMock, patch
 
 import pytest
+from deprecation import DeprecatedWarning
 from fastapi.testclient import TestClient
 
 from openhands.agent_server.api import _get_root_path, api_lifespan, create_app
 from openhands.agent_server.config import Config
 
 
+@pytest.fixture(autouse=True)
+def clear_web_url_env(monkeypatch):
+    monkeypatch.delenv("OH_WEB_URL", raising=False)
+    monkeypatch.delenv("RUNTIME_URL", raising=False)
+
+
 class TestStaticFilesServing:
     """Test static files serving functionality."""
 
@@ -403,21 +411,55 @@ class TestConfigWebUrl:
     """Tests for web_url configuration field."""
 
     def test_web_url_default_is_none_when_env_not_set(self):
-        """Test that web_url defaults to None when RUNTIME_URL is not set."""
-        # Ensure the env var is not set
+        """Test that web_url defaults to None when no env vars are set."""
         with patch.dict("os.environ", {}, clear=True):
             config = Config()
             assert config.web_url is None
 
-    def test_web_url_reads_from_runtime_url_env(self):
-        """Test that web_url reads from RUNTIME_URL environment variable."""
-        with patch.dict("os.environ", {"RUNTIME_URL": "https://test.example.com/path"}):
+    def test_web_url_reads_from_oh_web_url_env(self):
+        """Test that web_url reads from the canonical OH_WEB_URL env var."""
+        with patch.dict("os.environ", {"OH_WEB_URL": "https://test.example.com/path"}):
             config = Config()
             assert config.web_url == "https://test.example.com/path"
 
+    def test_web_url_reads_from_runtime_url_env_with_warning(self):
+        """Test that legacy RUNTIME_URL still works but emits a deprecation warning."""
+        with patch.dict("os.environ", {"RUNTIME_URL": "https://test.example.com/path"}):
+            with pytest.warns(DeprecatedWarning) as caught:
+                config = Config()
+
+        assert config.web_url == "https://test.example.com/path"
+        assert "RUNTIME_URL environment variable is deprecated" in str(
+            caught[0].message
+        )
+        assert "OH_WEB_URL" in str(caught[0].message)
+        assert "removed in 1.19.0" in str(caught[0].message)
+
+    def test_web_url_prefers_oh_web_url_over_runtime_url(self):
+        """Test that the canonical env var wins without warnings."""
+        with patch.dict(
+            "os.environ",
+            {
+                "OH_WEB_URL": "https://preferred.example.com/path",
+                "RUNTIME_URL": "https://legacy.example.com/path",
+            },
+        ):
+            with warnings.catch_warnings(record=True) as caught:
+                warnings.simplefilter("always")
+                config = Config()
+
+        assert config.web_url == "https://preferred.example.com/path"
+        assert caught == []
+
     def test_web_url_can_be_set_explicitly(self):
-        """Test that web_url can be set explicitly, overriding env var."""
-        with patch.dict("os.environ", {"RUNTIME_URL": "https://env.example.com"}):
+        """Test that web_url can be set explicitly, overriding env vars."""
+        with patch.dict(
+            "os.environ",
+            {
+                "OH_WEB_URL": "https://env.example.com/oh",
+                "RUNTIME_URL": "https://env.example.com/runtime",
+            },
+        ):
             config = Config(web_url="https://explicit.example.com/custom")
             assert config.web_url == "https://explicit.example.com/custom"