Argentina (B), Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guyana, Panama, Peru, Suriname, Trinidad and Tobago, Uruguay (B), Venezuela.
Extreme south-eastern Nicaragua south to Colombia, Venezuela, Trinidad, the Guianas, Amazonian Brazil (Acre, Rondônia, Amapá, Pará, northern Tocantins and Maranhío), north-western and north-eastern Ecuador, Peru (Loreto; Madre de Dios), and north-eastern Bolivia (Pando, Beni).
 
Population
Estimated population is unknown (2010).
Red-breasted Blackbird (Leistes militaris) [XC257157]
by Daniel F. Lane from Madre de Dios: ca.13 km SW of Puerto Maldonado, Peru (flight song, song)
Red-breasted Blackbird (Leistes militaris) [XC710771]
by Frank Lambert from Cana\u00e3 dos Caraj\u00e1s, State of Par\u00e1, Brazil (call)
Subspecies
No subspecies.
Formerly placed with White-browed Blackbird (Leistes superciliaris) in a separate genus, Leistes, but molecular data indicate close affinity with present genus. Closely related to White-browed Blackbird (Leistes superciliaris), and the two may form a superspecies. Sometimes considered conspecific, but ranges overlap locally in south-eastern Peru (eastern Madre de Dios), north-eastern Bolivia (Pando and northern Beni) and north-eastern Brazil (north-eastern Pará, Maranhío and northern Tocantins) with no evidence of interbreeding, and no intermediates or hybrids between the two have been reported. Range overlap sometimes attributed to seasonal northern movements by White-browed Blackbird (Leistes superciliaris), but verification is required.