Pseudolycaena marsyas has a wingspan of about, a quite huge size in hairstreaks. The uppersides of the wings are usually metallic blue, with hues varying from cobalt blue to turquoise blue depending on location. The apex of the wings are black and lightly falcade in males and the hindwings are tailed in both sexes, with a small black spot. The undersides of the wings are pale blue greyish, with several black spots and thin markings.