diff --git a/specification/webpubsub/data-plane/WebPubSub/preview/2021-05-01-preview/webpubsub.json b/specification/webpubsub/data-plane/WebPubSub/preview/2021-05-01-preview/webpubsub.json
index 72763727940d..4a0f815a36db 100644
--- a/specification/webpubsub/data-plane/WebPubSub/preview/2021-05-01-preview/webpubsub.json
+++ b/specification/webpubsub/data-plane/WebPubSub/preview/2021-05-01-preview/webpubsub.json
@@ -4,6 +4,15 @@
     "title": "Azure Web PubSub Service REST API",
     "version": "2021-05-01-preview"
   },
+  "x-ms-parameterized-host": {
+    "hostTemplate": "{Endpoint}",
+    "useSchemePrefix": false,
+    "parameters": [
+      {
+        "$ref": "#/parameters/Endpoint"
+      }
+    ]
+  },
   "paths": {
     "/api/health": {
       "head": {
@@ -907,5 +916,16 @@
         }
       }
     }
+  },
+  "parameters": {
+    "Endpoint": {
+      "name": "Endpoint",
+      "description": "HTTP or HTTPS endpoint for the Web PubSub service instance.",
+      "x-ms-parameter-location": "client",
+      "required": true,
+      "type": "string",
+      "in": "path",
+      "x-ms-skip-url-encoding": true
+    }
   }
 }
diff --git a/specification/webpubsub/data-plane/WebPubSub/preview/2021-08-01-preview/webpubsub.json b/specification/webpubsub/data-plane/WebPubSub/preview/2021-08-01-preview/webpubsub.json
index 722bac5465ee..7a39c680cce3 100644
--- a/specification/webpubsub/data-plane/WebPubSub/preview/2021-08-01-preview/webpubsub.json
+++ b/specification/webpubsub/data-plane/WebPubSub/preview/2021-08-01-preview/webpubsub.json
@@ -4,6 +4,15 @@
     "title": "Azure Web PubSub Service REST API",
     "version": "2021-08-01-preview"
   },
+  "x-ms-parameterized-host": {
+    "hostTemplate": "{Endpoint}",
+    "useSchemePrefix": false,
+    "parameters": [
+      {
+        "$ref": "#/parameters/Endpoint"
+      }
+    ]
+  },
   "paths": {
     "/api/health": {
       "head": {
@@ -985,5 +994,16 @@
         }
       }
     }
+  },
+  "parameters": {
+    "Endpoint": {
+      "name": "Endpoint",
+      "description": "HTTP or HTTPS endpoint for the Web PubSub service instance.",
+      "x-ms-parameter-location": "client",
+      "required": true,
+      "type": "string",
+      "in": "path",
+      "x-ms-skip-url-encoding": true
+    }
   }
 }