diff --git a/schema/rockcraft.json b/schema/rockcraft.json
index 261a59116..91bef9323 100644
--- a/schema/rockcraft.json
+++ b/schema/rockcraft.json
@@ -13720,6 +13720,18 @@
         "echo [ Hello ]"
       ],
       "title": "Entrypoint-Command"
+    },
+    "extensions": {
+      "type": "array",
+      "items": {
+        "type": "string"
+      },
+      "description": "List of extensions to apply to the rock.",
+      "examples": [
+        [
+          "twelve-factor"
+        ]
+      ]
     }
   },
   "required": [
diff --git a/tools/schema/schema.py b/tools/schema/schema.py
index 4c813b8d2..b21cad1cb 100755
--- a/tools/schema/schema.py
+++ b/tools/schema/schema.py
@@ -55,6 +55,14 @@ def generate_project_schema() -> str:
     # combine both schemas
     project_schema = {**initial_schema, **project_schema}
 
+    # add extensions field (DX only)
+    project_schema["properties"]["extensions"] = {
+        "type": "array",
+        "items": {"type": "string"},
+        "description": "List of extensions to apply to the rock.",
+        "examples": [["twelve-factor"]],
+    }
+
     # tweak the platforms definition on the Project (each value can be empty)
     project_schema["properties"]["platforms"]["additionalProperties"] = {
         "oneOf": [{"type": "null"}, {"$ref": "#/$defs/Platform"}]