In 2020 the North American Classification Committee of the American Ornithological Society (AOS), the International Ornithological Committee (IOC), and the Clements taxonomy placed it in genus Cynanthus with Carnivet's emerald, broad-billed hummingbird (C. latirostris), Turquoise-crowned hummingbird (C. doubledayi), and the Cozumel emerald (C. forficatus).

The tail is long and deeply forked; its feathers are black with a violet-bluish gloss, and the central three pairs have broad brownish gray tips.

[5] The golden-crowned emerald is found in western Mexico from Sinaloa south to eastern Oaxaca and also inland up the Balsas River basin to southern Morelos.

[5] The golden-crowned emerald is mostly resident but is thought to make some seasonal elevational movements in a few areas.

[5] The golden-crowned emerald is a "trap-line" feeder, visiting a circuit of flowering plants to take nectar.

The cup was made of kapok seed fibers with grass, bits of wood, and lichens on the outside.