Like other yellowthroats it forages low in vegetation and feeds on insects and other small invertebrates.

The Belding's yellowthroat is 14 cm long with an olive-green back and bright yellow belly.

This race has been drastically affected by habitat loss, and is now restricted to several small marshes in southernmost Baja California [the estero at San Jose del Cabo and the lagoon at Todo Santos; August, 2007].

The male of the northern subspecies G. b.goldmaii has a pale belly and grey forecrown, making it very similar to some non-migratory southwestern races of common yellowthroat, which, however, do not overlap in range.

It is larger and slightly brighter than the migratory races of common yellowthroat which winter in Baja California, and the male's mask extends further onto the nape than is the case with the visitors.