Tamandua mexicana is much smaller than giant anteaters (Myrmecophaga tridactyla). Head and body length ranges from 470 to 770 mm and tail length from 402 to 672 mm. Northern tamanduas are fawn to brownish colored and have a distinct, black "V" going down their backs. One of their names, vested anteaters, is derived from this "V" as it makes the anteater appear to be wearing a vest. Northern tamanduas always have this vivid, black "vest" on their trunk that continues from the shoulders to the rump. Southern tamanduas, northern tamandua's closest relative, only has this "V" in some specimens from the southeastern portion of their range, the part of their range which is farthest from the range of northern tamanduas. Sometimes the two species can only be distinguished by characters of the skull.

Pelage of T. mexicana is short, coarse, dense, and very bristly. The mouth opening is only about the diameter of a pencil, but the tongue can extend 40 cm. The tail is naked and prehensile, with irregular, black markings. On each hand there are four clawed digits. These claws range from 4 to 10 cm in length and are used for defense and slashing open termite and ant nests. The claw on the third digit is the longest, and the claw on the first digit is the smallest. The feet each have five clawed digits. The ears are large and protruding, but the eyes are very small.

Range mass: 2 to 7 kg.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

Average basal metabolic rate: 5.124 W.