Jorunna osae is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusc in the family Discodorididae.

This species was described from Playa Gallardo, Golfito, Osa Conservation Area, Costa Rica, Pacific Ocean.

Additional specimens from Tempisque Conservation Area and Osa Conservation Area are listed in the original description.

Most of the specimens are from the intertidal region with one from 9–13 m depth.

It is reported to reach 8 mm in length.