diff --git a/backend/open_webui/utils/oauth.py b/backend/open_webui/utils/oauth.py
index 1ef5268bae..b300ab57e9 100644
--- a/backend/open_webui/utils/oauth.py
+++ b/backend/open_webui/utils/oauth.py
@@ -241,6 +241,61 @@ def is_in_blocked_groups(group_name: str, groups: list) -> bool:
     return False
 
 
+async def discover_authorization_server_from_mcp(mcp_server_url: str) -> list[str]:
+    """
+    Discover OAuth authorization servers by following the MCP Protected Resource flow.
+
+    According to the MCP spec (https://modelcontextprotocol.io/specification/2025-03-26/basic/authorization):
+    1. Make an unauthenticated request to the MCP endpoint
+    2. Parse WWW-Authenticate header to get resource_metadata URL
+    3. Fetch Protected Resource metadata to get authorization_servers
+
+    Returns:
+        List of authorization server base URLs, or empty list if discovery fails
+    """
+    authorization_servers = []
+
+    try:
+        # Step 1: Make unauthenticated request to MCP endpoint to get WWW-Authenticate header
+        async with aiohttp.ClientSession(trust_env=True) as session:
+            async with session.post(
+                mcp_server_url,
+                json={"jsonrpc": "2.0", "method": "initialize", "params": {}, "id": 1},
+                headers={"Content-Type": "application/json"},
+                ssl=AIOHTTP_CLIENT_SESSION_SSL,
+            ) as response:
+                if response.status == 401:
+                    www_auth = response.headers.get("WWW-Authenticate", "")
+
+                    # Parse resource_metadata from WWW-Authenticate header
+                    # Format: Bearer resource_metadata="https://..."
+                    match = re.search(r'resource_metadata="([^"]+)"', www_auth)
+                    if match:
+                        resource_metadata_url = match.group(1)
+                        log.debug(f"Found resource_metadata URL: {resource_metadata_url}")
+
+                        # Step 2: Fetch Protected Resource metadata
+                        async with session.get(
+                            resource_metadata_url, ssl=AIOHTTP_CLIENT_SESSION_SSL
+                        ) as resource_response:
+                            if resource_response.status == 200:
+                                resource_metadata = await resource_response.json()
+
+                                # Step 3: Extract authorization_servers
+                                servers = resource_metadata.get(
+                                    "authorization_servers", []
+                                )
+                                if servers:
+                                    authorization_servers = servers
+                                    log.debug(
+                                        f"Discovered authorization servers: {servers}"
+                                    )
+    except Exception as e:
+        log.debug(f"MCP Protected Resource discovery failed: {e}")
+
+    return authorization_servers
+
+
 def get_parsed_and_base_url(server_url) -> tuple[urllib.parse.ParseResult, str]:
     parsed = urllib.parse.urlparse(server_url)
     base_url = f"{parsed.scheme}://{parsed.netloc}"
@@ -303,9 +358,29 @@ async def get_oauth_client_info_with_dynamic_client_registration(
             response_types=["code"],
         )
 
+        # First, try MCP Protected Resource discovery flow
+        # This handles cases where the OAuth server is on a different domain than the MCP server
+        # (e.g., Todoist MCP at ai.todoist.net, OAuth at todoist.com)
+        authorization_servers = await discover_authorization_server_from_mcp(
+            oauth_server_url
+        )
+
+        # Build discovery URLs - prioritize authorization servers from MCP discovery
+        all_discovery_urls = []
+        for auth_server in authorization_servers:
+            auth_server = auth_server.rstrip("/")
+            all_discovery_urls.extend(
+                [
+                    f"{auth_server}/.well-known/oauth-authorization-server",
+                    f"{auth_server}/.well-known/openid-configuration",
+                ]
+            )
+
+        # Fall back to standard discovery URLs based on the MCP server URL
+        all_discovery_urls.extend(get_discovery_urls(oauth_server_url))
+
         # Attempt to fetch OAuth server metadata to get registration endpoint & scopes
-        discovery_urls = get_discovery_urls(oauth_server_url)
-        for url in discovery_urls:
+        for url in all_discovery_urls:
             async with aiohttp.ClientSession(trust_env=True) as session:
                 async with session.get(
                     url, ssl=AIOHTTP_CLIENT_SESSION_SSL