Varnish is a mixture used primarily to coat wood.
Varnish may also refer to:
- Varnish (software), a reverse proxy and HTTP accelerator
- Jessica Varnish, British track cyclist
- Desert varnish, a coating found on exposed rock surfaces in arid environments
- Fluoride varnish, applied to the tooth's surface in dentistry
- Conformal coating, a type of PCB coating