Blue-necked Tanager has a disjunct distribution. It occurs on the lower slopes of the Andes from Venezuela and Colombia south, on the west side of the Andes, to western Ecuador(south to El Oro), and, on the east side of the Andes, south to Cochabamba, Bolivia (Storer 1970, Hilty and Brown 1986, Isler and Isler 1987, Ridgely and Greenfield 2001a, Hennessey et al. 2003, Hilty 2003). In addition, the species also occurs in the lowlands of southern Amazonia, from eastern Bolivia east across central Brazil to southern Pará and Mato Grosso, with an apparently isolated population in Goiás (Traylor 1950, Storer 1970, Isler and Isler 1987, Marantz and Remsen 1994).
Blue-necked Tanager occurs in the following zoogeographic regions: the Northern Andes, the Central Andes, Southern Amazonia, and Central South America (Parker et al. 1996).
The elevational range of Blue-necked Tanager in the Andes is from 100-2100 m in Venezuela, although it is most common from 300-1700 m (Hilty 2003); in Colombia, at 900-2400 m, although on the Pacific slope in Valle it occurs as low as 400 m (Hilty and Brown 1986); it occurs in western Ecuador from the lowlands up to 1400 m, and in eastern Ecuador from 500-1800 m (Ridgely and Greenfield 2001a); in Peru the elevational range is 800-2000 m, although locally it occurs as 350 m, especially in southern Peru (Schulenberg et al. 2007); and in Bolivia it occurs up to 1600 m (Hennessey et al. 2003).