We describe a striking new species of the microhylid frog genus Mantophryne from Woodlark Island in Milne Bay Province, Papua New Guinea. It is most similar to M. lateralis but is distinguished from that species by its more slender body, longer shanks, larger discs on the toes, and unique advertisement call. Most known specimens had, in life, a striking golden tan mid-dorsum bordered by broad blackish dorsolateral bands. The new species is currently known only from the rainforests of Woodlark Island, where males call from elevated perches up to 4 m above the ground from climbing Freycinetia plants, from crevices and hollows in elevated limestone outcrops, and from tree buttresses and on top of fallen logs on the forest floor. It is the most arboreal member of this predominantly terrestrial genus discovered to date.