The turquoise tanager was formally described in 1766 by the Swedish naturalist Carl Linnaeus in the 12th edition of his Systema Naturae under the binomial name Tanagra mexicana.

[3] His description was principally based on Mathurin Jacques Brisson's Le tangara blue de Cayenne that he had described and illustrated in 1760.

[7] Adult turquoise tanagers are 14 cm (5.5 in) long and weigh 20 g. They are long-tailed and with a dark stout pointed bill.

Most races have yellow lower underparts, but this is paler, more cream, in the nominate subspecies found in north-eastern South America.

The Trinidadian race, T. m. vieiloti, has a darker blue head and breast and more vividly yellow underparts than the mainland taxa.