diff --git a/src/taskgraph/util/verify.py b/src/taskgraph/util/verify.py
index e4b9a530d..d7d60bacd 100644
--- a/src/taskgraph/util/verify.py
+++ b/src/taskgraph/util/verify.py
@@ -224,6 +224,25 @@ def verify_routes_notification_filters(
                 )
 
 
+@verifications.add("full_task_graph")
+def verify_index_route(task, taskgraph, scratch_pad, graph_config, parameters):
+    """
+    This function ensures that routes do not contain forward slashes.
+    """
+    if task is None:
+        return
+    task_dict = task.task
+    routes = task_dict.get("routes", [])
+    route_prefix = "index."
+
+    for route in routes:
+        # Check for invalid / in the index route
+        if route.startswith(route_prefix) and "/" in route:
+            raise Exception(
+                f"{task.label} has invalid route with forward slash: {route}"
+            )
+
+
 @verifications.add("full_task_graph")
 def verify_dependency_tiers(task, taskgraph, scratch_pad, graph_config, parameters):
     tiers = scratch_pad
diff --git a/test/test_util_verify.py b/test/test_util_verify.py
index 682179505..83cca3899 100644
--- a/test/test_util_verify.py
+++ b/test/test_util_verify.py
@@ -199,6 +199,21 @@ def make_task_treeherder(label, symbol, platform="linux/opt"):
             DeprecationWarning,
             id="routes_notfication_filter: deprecated",
         ),
+        pytest.param(
+            "verify_index_route",
+            make_graph(
+                make_task(
+                    "invalid_slash",
+                    task_def={
+                        "routes": [
+                            "index.example.com/foobar.v2.latest.taskgraph.decision"
+                        ]
+                    },
+                ),
+            ),
+            Exception,
+            id="verify_index_route: invalid slash in route",
+        ),
     ),
 )
 @pytest.mark.filterwarnings("error")