Felimare lajensis is a species of sea slug or dorid nudibranch, a marine gastropod mollusc in the family Chromodorididae.

[3] Felimare lajensis is dark blue in colour with a series of yellow longitudinal lines.

The edge of the mantle is white and there is a series of darker blue spots on a blue background between the border and the first of the yellow lines.

The maximum recorded body length is 30 mm.

[4] Minimum recorded depth is 7.3 m.[4] Maximum recorded depth is 25 m.[4] This species feeds on a blue species of sponge, Dysidea etheria.