Phyllidia scottjohnsoni is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusk in the family Phyllidiidae.

[2] This species was described from the Hawaiian Islands.

[3] This nudibranch has a partly translucent, white dorsum with large round black spots.

There are small, scattered, tubercles all over the back.

[3][4] This species feeds on a sponge.