[5] The black-breasted puffleg is endemic to north-western Ecuador, where it currently appears restricted to the ridge crests of the Pichincha Volcano, the Cordillera de Toisán, Esmeraldas and Imbabura.

[6] The birds are altitudinal migrants, generally being found at altitudes of 2440–3050 m between April and September, but remaining above 3100 m during the breeding season from November to February, although more recent observations suggest that migration patterns may fluctuate or change.

Although the black-breasted puffleg has recently been rediscovered in small populations outside its main range on the Pichincha volcano, its total area of occurrence is estimated as 100 km2.

Of the habitat in its original range, 93–97% are considered to have been degraded or destroyed by agricultural expansion, logging and cattle grazing, and these practices remain the main threats to the species, together with natural and human-induced fires.

[1] A primary source of habitat loss has been the construction of the Oleoducto de Crudos Pesados (OCP) for oil transportation, a route that was established through one of the last remnants of forest.

[11] In 2020, the Fundación Jocotoco started a new project with the National Geographic Society focusing on habitat enrichment, protection, and restoration for the hummingbird, in conjunction with local communities in the region.