diff --git a/src/fastmcp/client/transports.py b/src/fastmcp/client/transports.py
index 81afc9c88..59d22c7e7 100644
--- a/src/fastmcp/client/transports.py
+++ b/src/fastmcp/client/transports.py
@@ -974,12 +974,23 @@ class MCPConfigTransport(ClientTransport):
     async def connect_session(
         self, **session_kwargs: Unpack[SessionKwargs]
     ) -> AsyncIterator[ClientSession]:
-        async with self.transport.connect_session(**session_kwargs) as session:
-            yield session
+        try:
+            async with self.transport.connect_session(**session_kwargs) as session:
+                yield session
+        finally:
+            # Clean up underlying transports to ensure subprocesses terminate
+            # Use gather with return_exceptions to ensure all transports close even if one fails
+            await asyncio.gather(
+                *(transport.close() for transport in self._underlying_transports),
+                return_exceptions=True,
+            )
 
     async def close(self):
-        for transport in self._underlying_transports:
-            await transport.close()
+        # Use gather with return_exceptions to ensure all transports close even if one fails
+        await asyncio.gather(
+            *(transport.close() for transport in self._underlying_transports),
+            return_exceptions=True,
+        )
 
     def __repr__(self) -> str:
         return f"<MCPConfigTransport(config='{self.config}')>"
diff --git a/tests/test_mcp_config.py b/tests/test_mcp_config.py
index 41924813b..1c1c7a6c4 100644
--- a/tests/test_mcp_config.py
+++ b/tests/test_mcp_config.py
@@ -340,17 +340,12 @@ async def test_multi_client_lifespan(tmp_path: Path):
 
     gc_collect_harder()
 
-    # This test will fail while debugging because the debugger holds a reference to the underlying transport
+    # Verify processes have terminated
+    with pytest.raises(psutil.NoSuchProcess):
+        psutil.Process(pid_1).status()
 
     with pytest.raises(psutil.NoSuchProcess):
-        while True:
-            psutil.Process(pid_1)
-            await asyncio.sleep(0.01)
-
-    with pytest.raises(psutil.NoSuchProcess):
-        while True:
-            psutil.Process(pid_2)
-            await asyncio.sleep(0.01)
+        psutil.Process(pid_2).status()
 
 
 @pytest.mark.skipif(