diff --git a/sanic_ext/extensions/openapi/blueprint.py b/sanic_ext/extensions/openapi/blueprint.py
index 7bd164b..b5b8691 100644
--- a/sanic_ext/extensions/openapi/blueprint.py
+++ b/sanic_ext/extensions/openapi/blueprint.py
@@ -1,4 +1,5 @@
 import inspect
+from copy import deepcopy
 
 from functools import lru_cache, partial
 from os.path import abspath, dirname, realpath
@@ -192,6 +193,10 @@ def build_spec(app):
                 ):
                     operation.autodoc(docstring)
 
+                # Create an operation per method so defaults (like operationId)
+                # do not overwrite each other for multi-method routes.
+                operation = deepcopy(operation)
+
                 operation._default["operationId"] = (
                     f"{method.lower()}~{route_name}"
                 )
diff --git a/sanic_ext/utils/route.py b/sanic_ext/utils/route.py
index d5e6e46..0a643da 100644
--- a/sanic_ext/utils/route.py
+++ b/sanic_ext/utils/route.py
@@ -111,7 +111,8 @@ def get_all_routes(app, skip_prefix):
                     continue
 
                 method_handlers = [
-                    (method, route.handler) for method in route.methods
+                    (method, route.handler)
+                    for method in sorted(route.methods)
                 ]
 
                 _, name = route.name.split(".", 1)
diff --git a/tests/extensions/openapi/test_operation_id.py b/tests/extensions/openapi/test_operation_id.py
new file mode 100644
index 0000000..0e3e862
--- /dev/null
+++ b/tests/extensions/openapi/test_operation_id.py
@@ -0,0 +1,15 @@
+from sanic import Sanic
+
+from .utils import get_spec
+
+
+def test_operation_id_is_unique_per_method_and_deterministic(app: Sanic):
+    @app.route("/ping", methods=["GET", "POST"])
+    async def ping(_):
+        return {"ping": "pong"}
+
+    spec = get_spec(app)
+    path = spec["paths"]["/ping"]
+
+    assert path["get"]["operationId"] == "get~ping"
+    assert path["post"]["operationId"] == "post~ping"