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

This species was described from Okinawa, Ryukyu Islands, Japan.

[2] This Okenia has a narrow body and seven pairs of long lateral papillae.

There are two papillae on the mid-line of the back, in front of the gills.

The diet of this species is the ctenostome bryozoan, Amathia sp.