Gray brocket deer range from 850 to 1050 mm in total body length, stand around 650 mm at the shoulder. They weigh approximately of 17kg.
Gray brocket deer are slightly smaller than red brocket deer (Mazama americana). The gray brocket deer also has a straighter back, giving its silhouette a more deer-like shape.
Mazama gouazoupira has a grayish-brown to reddish-brown coat. The males have simple antlers about 70 to 100 mm in length. The undersides of the tail is white, with the pelage on the flanks being of a paler color. ()