Brazil, French Guiana, Guyana, Suriname, Venezuela.
South-eastern Venezuela (eastern Bolívar), the Guianas, and north-eastern Brazil from Manaus eastern (on both sides of R Amazon) to Pará and northern Maranhío.
 
Population
Estimated population is unknown (2010).
Golden-sided Euphonia (Euphonia cayennensis) [XC518838]
by id from Roura, Montagne des Chevaux, French Guiana (song)
Golden-sided Euphonia (Euphonia cayennensis) [XC540911]
by Brice de la Croix from Cabo Frio camp -- Biological Dynamics of Forest Fragments Project, Brazil (song)
Subspecies
Recent molecular-genetic analysis indicates that genus belongs in family Fringillidae. May form a superspecies with Rufous-bellied Euphonia (Euphonia rufiventris) and Chestnut-bellied Euphonia (Euphonia pectoralis).