Golden-naped Tanager is omnivorous, and feeds on arthropods, fruit, Müllerian bodies, and nectar. The proportions of food eaten by the Golden-naped Tanager were recorded (Naoki 2002) from Mindo, Ecuador (n = 231). The diet during this study was composed of 67% arthropods, 21% fruits, 7% Müllerian bodies, and 4% nectar.

Naoki (2007) quantified the relationship between diet and habitat and found that, regardless of whether it is foraging on arthropods or fruit, the species mainly forages in secondary forest:

Primary modes of foraging for arthropods include sallying (74% of observations) and gleaning (18%) (Naoki 2003). Likewise, the primary substrate is air (59%) as well as leaves (29%) and flower buds (10%) (Naoki 2003). When fruit-foraging, gleaning (65%) is the primary mode used. Other foraging modes include hang-side (16%) and reach-down (10%) (Naoki 2003). Golden-naped Tanager prefers fruits from Ficus, Micornia, Morus and Cecropia species (Isler and Isler 1987, Naoki 2003). It also is one of only a few species to develop a mutualistic relationship with the plant species Cecropia gabrielis. Naoki and Toapanta (2001) hypothesized that the Golden-naped Tanager benefits from eating the Müllerian bodies produced by C. gabrielis while the plant benefits from the omnivorous bird eating herbivorous insects that cause it harm.