The Crescent Honeyeater is a medium to small honeyeater with a long down-curved bill and a red-brown eye. Males are dark grey above with yellow wing patches, a white streak above the eye and a distinctive dark crescent across each side of the breast, outlined below with a white line. The rest of the underparts are a pale brown grey to white, with prominent white markings on the tail. Females are smaller and are olive brown above, with an olive brown crescent on each side of the breast, white to brown grey underparts, and olive yellow wing patches. Young birds resemble adults, but lack strong breast markings.