The sungrebe was described by the French polymath Georges-Louis Leclerc, Comte de Buffon in 1781 in his "Histoire Naturelle des Oiseaux" from a specimen collected in Cayenne, French Guiana. The bird was also illustrated in a hand-coloured plate engraved by François-Nicolas Martinet in the "Planches Enluminées D'Histoire Naturelle" which was produced under the supervision of Edme-Louis Daubenton to accompany Buffon's text. Neither the plate caption nor Buffon's description included a scientific name but in 1783 the Dutch naturalist Pieter Boddaert coined the binomial name "Colymbus fulica" in his catalogue of the "Planches Enluminées". The sungrebe is now the only species placed in the genus "Heliornis" that was erected by the French naturalist Pierre Bonnaterre in 1791 with the sungrebe as the type species. The name of the genus combines the Ancient Greek "hēlios" meaning "sun" and "ornis " meaning "bird". The specific epithet "fulica" is Latin for "coot". No subspecies are recognised.