It is found in Argentina, Bolivia, Brazil, Colombia, Guyana, Suriname, and Venezuela.

[5] The least nighthawk is 15 to 25 cm (5.9 to 9.8 in) long, making it one of the smallest species in family Caprimulgidae.

Two females weighed 27.8 and 33.4 g (0.98 and 1.18 oz) The general plumage pattern is brown upperparts with gray, rufous, and buff spots, and whitish or buff underparts with brown bars.

[2][5] The least nighthawk typically inhabits open savanna or subtropical grassland, both cerrado and caatinga.

The least nighthawk's flight call has been variously described as "a low churr and a weak nasal beep or week" and as "a short, sharp whit or bit".