Okenia vena is a species of sea slug, specifically a dorid nudibranch, a marine gastropod mollusc in the family Goniodorididae.

This species was described from northern New South Wales, Australia.

The body is white and the rhinophores are brown.

There is a pattern of broken brown lines on the back and tail.

The diet of this species is the ctenostome bryozoan Amathia tortuosa.