Byrknesøyna is an island in Gulen Municipality in Vestland county, Norway.

Almost all of the inhabitants live in the village of Byrknes on the northwestern coast of the island.

There are thousands of small (mostly uninhabited) islets surrounding Byrknesøyna.

The highest point on the island is the 194-metre (636 ft) tall Veten.

The island is covered by a typical western Norwegian heather moorland.