diff --git a/src/taskgraph/util/keyed_by.py b/src/taskgraph/util/keyed_by.py
index 00c84ba98..226b0194f 100644
--- a/src/taskgraph/util/keyed_by.py
+++ b/src/taskgraph/util/keyed_by.py
@@ -2,8 +2,40 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+from typing import Any, Dict, Generator, Tuple
 
-from .attributes import keymatch
+from taskgraph.util.attributes import keymatch
+
+
+def iter_dot_path(
+    container: Dict[str, Any], subfield: str
+) -> Generator[Tuple[dict[str, Any], str], None, None]:
+    """Given a container and a subfield in dot path notation, yield the parent
+    container of the dotpath's leaf node, along with the leaf node name that it
+    contains.
+
+    If the dot path contains a list object, each item in the list will be
+    yielded.
+
+    Args:
+        container (dict): The container to search for the dot path.
+        subfield (str): The dot path to search for.
+    """
+    while "." in subfield:
+        f, subfield = subfield.split(".", 1)
+
+        if f not in container:
+            return
+
+        if isinstance(container[f], list):
+            for item in container[f]:
+                yield from iter_dot_path(item, subfield)
+            return
+
+        container = container[f]
+
+    if isinstance(container, dict) and subfield in container:
+        yield container, subfield
 
 
 def evaluate_keyed_by(
diff --git a/src/taskgraph/util/schema.py b/src/taskgraph/util/schema.py
index 8b2b59051..590273676 100644
--- a/src/taskgraph/util/schema.py
+++ b/src/taskgraph/util/schema.py
@@ -10,8 +10,7 @@
 import voluptuous
 
 import taskgraph
-
-from .keyed_by import evaluate_keyed_by
+from taskgraph.util.keyed_by import evaluate_keyed_by, iter_dot_path
 
 
 def validate_schema(schema, obj, msg_prefix):
@@ -125,26 +124,14 @@ def resolve_keyed_by(
     Returns:
         dict: item which has also been modified in-place.
     """
-    # find the field, returning the item unchanged if anything goes wrong
-    container, subfield = item, field
-    while "." in subfield:
-        f, subfield = subfield.split(".", 1)
-        if f not in container:
-            return item
-        container = container[f]
-        if not isinstance(container, dict):
-            return item
-
-    if subfield not in container:
-        return item
-
-    container[subfield] = evaluate_keyed_by(
-        value=container[subfield],
-        item_name=f"`{field}` in `{item_name}`",
-        defer=defer,
-        enforce_single_match=enforce_single_match,
-        attributes=dict(item, **extra_values),
-    )
+    for container, subfield in iter_dot_path(item, field):
+        container[subfield] = evaluate_keyed_by(
+            value=container[subfield],
+            item_name=f"`{field}` in `{item_name}`",
+            defer=defer,
+            enforce_single_match=enforce_single_match,
+            attributes=dict(item, **extra_values),
+        )
 
     return item
 
diff --git a/test/test_util_keyed_by.py b/test/test_util_keyed_by.py
new file mode 100644
index 000000000..1a8ae5e79
--- /dev/null
+++ b/test/test_util_keyed_by.py
@@ -0,0 +1,29 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from pprint import pprint
+
+import pytest
+
+from taskgraph.util.keyed_by import iter_dot_path
+
+
+@pytest.mark.parametrize(
+    "container,subfield,expected",
+    (
+        pytest.param(
+            {"a": {"b": {"c": 1}}, "d": 2}, "a.b.c", [({"c": 1}, "c")], id="simple case"
+        ),
+        pytest.param(
+            {"a": [{"b": 1}, {"b": 2}, {"b": 3}], "d": 2},
+            "a.b",
+            [({"b": 1}, "b"), ({"b": 2}, "b"), ({"b": 3}, "b")],
+            id="list case",
+        ),
+    ),
+)
+def test_iter_dot_paths(container, subfield, expected):
+    result = list(iter_dot_path(container, subfield))
+    pprint(result, indent=2)
+    assert result == expected
diff --git a/test/test_util_schema.py b/test/test_util_schema.py
index c56f818ac..5a8d6df4f 100644
--- a/test/test_util_schema.py
+++ b/test/test_util_schema.py
@@ -106,6 +106,20 @@ def test_nested(self):
             {"x": {"by-bar": {"B1": 11, "B2": 12}}},
         )
 
+    def test_list(self):
+        item = {
+            "y": {
+                "by-foo": {
+                    "F1": 10,
+                    "F2": 20,
+                },
+            }
+        }
+        self.assertEqual(
+            resolve_keyed_by({"x": [item, item]}, "x.y", "name", foo="F1"),
+            {"x": [{"y": 10}, {"y": 10}]},
+        )
+
     def test_no_by_empty_dict(self):
         self.assertEqual(resolve_keyed_by({"x": {}}, "x", "n"), {"x": {}})