The Yellow-bellied Sunbird-Asity is a small bird of eastern Madagascar's mountain forests. In breeding plumage, the male has a glossy blue-black back, yellow underparts, and bright eye wattles.
The breeding male has glossy blue-black upperparts, bright yellow underparts, and large green-blue wattles around the eyes. The female is olive-green above and yellow below and lacks the wattles.
It feeds mainly on nectar and also catches small insects. It uses humid, mossy montane forest and may move to different elevations in the cold season.
An extinction-risk assessment has not been added yet.