diff --git a/.github/workflows/cicd.yaml b/.github/workflows/cicd.yaml
index 0cdf365..30b73f7 100644
--- a/.github/workflows/cicd.yaml
+++ b/.github/workflows/cicd.yaml
@@ -44,7 +44,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          python -m pip install .[dev,server]
+          python -m pip install .[dev,server,validation]
           python -m pip install "pypgstac==${{ matrix.pypgstac }}"
 
       - name: Run test suite
diff --git a/CHANGES.md b/CHANGES.md
index 64a15e9..4f1f7cd 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -48,6 +48,10 @@
 
 ### Added
 
+- add `validate_extensions` setting that enables validation of `stac_extensions` from submitted STAC objects
+  using the `stac_pydantic.extensions.validate_extensions` utility. Applicable only when `TransactionExtension`
+  is active.
+- add `validation` extra requirement to install dependencies of `stac_pydantic` required for extension validation
 - add `write_connection_pool` option in `stac_fastapi.pgstac.db.connect_to_db` function
 - add `write_postgres_settings` option in `stac_fastapi.pgstac.db.connect_to_db` function to set specific settings for the `writer` DB connection pool
 - add specific error message when trying to create `Item` with null geometry (not supported by PgSTAC)
diff --git a/setup.py b/setup.py
index 8005f5e..4eb1998 100644
--- a/setup.py
+++ b/setup.py
@@ -47,6 +47,9 @@
     ],
     "server": ["uvicorn[standard]==0.35.0"],
     "awslambda": ["mangum"],
+    "validation": [
+        "stac_pydantic[validation]",
+    ],
 }
 
 
diff --git a/stac_fastapi/pgstac/config.py b/stac_fastapi/pgstac/config.py
index 4f8f7da..00432af 100644
--- a/stac_fastapi/pgstac/config.py
+++ b/stac_fastapi/pgstac/config.py
@@ -170,6 +170,13 @@ class Settings(ApiSettings):
     invalid_id_chars: List[str] = DEFAULT_INVALID_ID_CHARS
     base_item_cache: Type[BaseItemCache] = DefaultBaseItemCache
 
+    validate_extensions: bool = False
+    """
+    Validate `stac_extensions` schemas against submitted data when creating or updated STAC objects.
+
+    Implies that the `Transactions` extension is enabled.
+    """
+
     cors_origins: str = "*"
     cors_methods: str = "GET,POST,OPTIONS"
     cors_credentials: bool = False
diff --git a/stac_fastapi/pgstac/transactions.py b/stac_fastapi/pgstac/transactions.py
index d2fe968..bb2588e 100644
--- a/stac_fastapi/pgstac/transactions.py
+++ b/stac_fastapi/pgstac/transactions.py
@@ -2,7 +2,7 @@
 
 import logging
 import re
-from typing import List, Optional, Union
+from typing import Any, Dict, List, Optional, Union
 
 import attr
 import jsonpatch
@@ -23,6 +23,7 @@
 from stac_fastapi.types import stac as stac_types
 from stac_fastapi.types.errors import NotFoundError
 from stac_pydantic import Collection, Item, ItemCollection
+from stac_pydantic.extensions import validate_extensions
 from starlette.responses import JSONResponse, Response
 
 from stac_fastapi.pgstac.config import Settings
@@ -44,8 +45,38 @@ def _validate_id(self, id: str, settings: Settings):
                 detail=f"ID ({id}) cannot contain the following characters: {' '.join(invalid_chars)}",
             )
 
+    def _validate_extensions(
+        self,
+        stac_object: Union[
+            stac_types.Item, stac_types.Collection, stac_types.Catalog, Dict[str, Any]
+        ],
+        settings: Settings,
+    ) -> None:
+        """Validate extensions of the STAC object data."""
+        if not settings.validate_extensions:
+            return
+
+        if isinstance(stac_object, dict):
+            if not stac_object.get("stac_extensions"):
+                return
+        else:
+            if not stac_object.stac_extensions:
+                return
+
+        try:
+            validate_extensions(
+                stac_object,
+                reraise_exception=True,
+            )
+        except Exception as err:
+            raise HTTPException(
+                status_code=422,
+                detail=f"STAC Extensions failed validation: {err!s}",
+            ) from err
+
     def _validate_collection(self, request: Request, collection: stac_types.Collection):
         self._validate_id(collection["id"], request.app.state.settings)
+        self._validate_extensions(collection, request.app.state.settings)
 
     def _validate_item(
         self,
@@ -59,6 +90,7 @@ def _validate_item(
         body_item_id = item.get("id")
 
         self._validate_id(body_item_id, request.app.state.settings)
+        self._validate_extensions(item, request.app.state.settings)
 
         if item.get("geometry", None) is None:
             raise HTTPException(
@@ -180,6 +212,7 @@ async def update_collection(
         """Update collection."""
 
         col = collection.model_dump(mode="json")
+        self._validate_collection(request, col)
 
         async with request.app.state.get_connection(request, "w") as conn:
             await dbfunc(conn, "update_collection", col)
diff --git a/tests/api/test_api.py b/tests/api/test_api.py
index bd2a364..7f67e28 100644
--- a/tests/api/test_api.py
+++ b/tests/api/test_api.py
@@ -948,3 +948,39 @@ async def test_default_app(default_client, default_app, load_test_data):
     assert "https://api.stacspec.org/v1.0.0/collections" in conf
     assert "https://api.stacspec.org/v1.0.0/ogcapi-features#query" in conf
     assert "https://api.stacspec.org/v1.0.0/ogcapi-features#sort" in conf
+
+
+async def test_app_transactions_validate_extension(
+    app_client_validate_ext, load_test_data
+):
+    coll = load_test_data("test_collection.json")
+    # Add attribution extension
+    # https://github.com/stac-extensions/attribution
+    coll["stac_extensions"] = [
+        "https://stac-extensions.github.io/attribution/v0.1.0/schema.json",
+    ]
+
+    resp = await app_client_validate_ext.post("/collections", json=coll)
+    assert resp.status_code == 422
+    assert "STAC Extensions failed validation:" in resp.json()["detail"]
+
+    # add attribution
+    coll["attribution"] = "something"
+    resp = await app_client_validate_ext.post("/collections", json=coll)
+    assert resp.status_code == 201
+
+    item = load_test_data("test_item.json")
+    item["stac_extensions"].append(
+        "https://stac-extensions.github.io/attribution/v0.1.0/schema.json",
+    )
+    resp = await app_client_validate_ext.post(
+        f"/collections/{coll['id']}/items", json=item
+    )
+    assert resp.status_code == 422
+    assert "STAC Extensions failed validation:" in resp.json()["detail"]
+
+    item["properties"]["attribution"] = "something"
+    resp = await app_client_validate_ext.post(
+        f"/collections/{coll['id']}/items", json=item
+    )
+    assert resp.status_code == 201
diff --git a/tests/conftest.py b/tests/conftest.py
index d349593..dbbb597 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -454,3 +454,48 @@ async def app_client_advanced_freetext(app_advanced_freetext):
         transport=ASGITransport(app=app_advanced_freetext), base_url="http://test"
     ) as c:
         yield c
+
+
+@pytest.fixture(scope="function")
+async def app_transaction_validation_ext(database):
+    """Default stac-fastapi-pgstac application with extension validation in transaction."""
+    api_settings = Settings(testing=True, validate_extensions=True)
+    api = StacApi(
+        settings=api_settings,
+        extensions=[
+            TransactionExtension(
+                client=TransactionsClient(),
+                settings=api_settings,
+            )
+        ],
+        client=CoreCrudClient(),
+        health_check=health_check,
+    )
+
+    postgres_settings = PostgresSettings(
+        pguser=database.user,
+        pgpassword=database.password,
+        pghost=database.host,
+        pgport=database.port,
+        pgdatabase=database.dbname,
+    )
+    logger.info("Creating app Fixture")
+    await connect_to_db(
+        api.app,
+        postgres_settings=postgres_settings,
+        add_write_connection_pool=True,
+    )
+    yield api.app
+    await close_db_connection(api.app)
+
+    logger.info("Closed Pools.")
+
+
+@pytest.fixture(scope="function")
+async def app_client_validate_ext(app_transaction_validation_ext):
+    logger.info("creating app_client")
+    async with AsyncClient(
+        transport=ASGITransport(app=app_transaction_validation_ext),
+        base_url="http://test",
+    ) as c:
+        yield c