The Choiseul pigeon was monotypic within the genus Microgoura and had no known subspecies. Its closest living relative is believed to be the thick-billed ground pigeon, and some authors have suggested that the Choiseul pigeon may be a link between that species and the crowned pigeons. The adult pigeon was largely blue-grey, with a buffy orange belly and a distinctive slaty-blue crest. It is unknown how this crest was held by the bird in life. The bird's head sported a blue frontal shield surrounded by black feathers and a bicoloured beak. The wings were brown and the short tail was a blackish purple. It was described as having a beautiful rising and falling whistling call.