Glossodoris rufomarginata has a commonly observed length of with a maximum length of . The background colouration of the entire body is whitish with the foot and the dorsal surface speckled with a dense coat of tiny red to orange-brown dots that give the impression at first glance that the animal is brown. The edge of the mantle is well developed and wavy with a broad white band with a red to orange-brown outer border. The foot has also a white external margin. The
rhinophores and branchial plume are retractable with a red to orange-brown colouration, a white median line on the
rhinophores and a white highlight on the
gill axes. ==Distribution and habitat==