The blue-necked tanager averages 12 cm (4.7 in) in length and weighs approximately 17 g (5⁄8 oz).

The diet of the blue-necked tanager consists of fruits, berries, flower blossoms and insects.

Tanagers will pick insects from leaves, or sometimes in flight, but fruit is the major dietary item.

The female builds a cup nest of moss, usually well concealed, and lays an average of 2 white eggs with brown spotting.

The male and female feed the nestlings on insects and fruit, and may be assisted by helpers.