The Joined Underwing has a wingspan of 2.75 to 3 inches. The forewing is gray with double dark marks along the costa. The light-colored subterminal line is zigzagged and outlined with black. There is a dark gray-brown band at the median line. There is brownish-yellow shading in the reniform and orbicular spots. The hindwing is light orange. The black median band is narrower than another large eastern underwings and usually does not reach the inner margin. The legs are black with white bands. The caterpillar is brown and elongated with a low medial hump on the 5th abdominal segment. There are orange projecting brows on the head.