Eastern and south-eastern Brazil (Alagoas; central Mato Grosso and southern Bahia south to Santa Catarina), adjacent eastern Paraguay and north-eastern Argentina (Misiones).
 
Population
Estimated population is unknown (2010).
Chestnut-bellied Euphonia (Euphonia pectoralis) [XC549035]
by id from PN Iguacu, Parana state, Brazil (song)
Chestnut-bellied Euphonia (Euphonia pectoralis) [XC556308]
by Caio Brito from Fazenda Folha Seca - Jonas, Brazil (canto)
Subspecies
Recent molecular-genetic analysis indicates that genus belongs in family Fringillidae. May form a superspecies with Rufous-bellied Euphonia (Euphonia rufiventris) and Golden-sided Euphonia (Euphonia cayennensis). Described taxon Euphonia vittata believed to have been a hybrid between present species and Orange-bellied Euphonia (Euphonia xanthogaster).