Hairy nightshade is a bushy plant that reaches 3-1/3 feet (0.9 m) tall. Perennial forms of the plant sometimes are slightly woody at the base. Althoughs leaves vary they are overall egg shaped with a smooth to wavy edge or an irregular, shallow-toothed edge. Leaves are alternate to one another along the stem. Leaves have numerous conspicuous, fine, short hairs, especially along the underside of the main vein, distinguishing it from black nightshade, which is inconspicuously covered with minute hairs.
Flowers bloom from May through October. Two to eight star-shaped, usually white flowers grow in a cluster. The inside of the petals sometimes are flecked with purple. Another species, silverleaf nightshade, S. elaeagnifolium, has colorful showy flowers.