diff --git a/CHANGES.md b/CHANGES.md
index cc40dddec..ac4ce9b01 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- add a third-party extensions section in the README and docs for the external `stac-fastapi-catalogs-extension` project ([#891](https://github.com/stac-utils/stac-fastapi/pull/891))
+
 ### Fixed
 
 - fix mypy type errors in transaction extension for Python 3.14 compatibility (mypy 1.20.0) ([#895](https://github.com/stac-utils/stac-fastapi/pull/895))
diff --git a/README.md b/README.md
index 0eac7da7d..8b4f888cc 100644
--- a/README.md
+++ b/README.md
@@ -51,6 +51,10 @@ Other implementations include:
 - [stac-fastapi-duckdb](https://github.com/Healy-Hyperspatial/stac-fastapi-duckdb): [DuckDB](https://github.com/duckdb/duckdb) (experimental)
 - [stac-fastapi-sqlalchemy](https://github.com/stac-utils/stac-fastapi-sqlalchemy): [PostgreSQL](https://github.com/postgres/postgres) + [PostGIS](https://github.com/postgis/postgis) via [SQLAlchemy](https://www.sqlalchemy.org/) (abandoned in favor of stac-fastapi-pgstac)
 
+#### Third-Party Extensions
+
+- [stac-fastapi-catalogs-extension](https://github.com/StacLabs/stac-fastapi-catalogs-extension): Multi-tenant virtual catalogs extension for STAC FastAPI deployments. It adds a dedicated `/catalogs` registry, scoped catalog routes, and an optional catalog management system for maintaining catalog hierarchies within one API.
+
 ## Response Model Validation
 
 A common question when using this package is how request and response types are validated?
diff --git a/docs/src/api/stac_fastapi/extensions/third_party/index.md b/docs/src/api/stac_fastapi/extensions/third_party/index.md
index 3ac6c5e1d..2f06401ec 100644
--- a/docs/src/api/stac_fastapi/extensions/third_party/index.md
+++ b/docs/src/api/stac_fastapi/extensions/third_party/index.md
@@ -2,6 +2,10 @@
 
 Third Party Extensions submodule.
 
+## Related External Projects
+
+* [stac-fastapi-catalogs-extension](https://github.com/StacLabs/stac-fastapi-catalogs-extension): Multi-tenant virtual catalogs extension for STAC FastAPI deployments, adding a dedicated `/catalogs` registry, scoped catalog routes, and an optional catalog management system for maintaining catalog hierarchies.
+
 ## Sub-modules
 
 * [stac_fastapi.extensions.third_party.bulk_transactions](bulk_transactions.md)