Three-toothed mitrewort is a small forest perennial with several stems arising from several basal leaves. The stems range from 15-35 cm in height and are usually leafless, although a much reduced leaf may occasionally be found near the base, and several small bracts above that. The herbage is often somewhat glandular-hairy. The leaf blades are heart-shaped to ovate heart-shaped with 5-7 indistinct lobes. The blade is 2-6 cm wide and the petioles are usually longer than the blades.

The inflorescence is a raceme of 10-20 closely spaced flowers. The flowers may tend to crowd to one side of the stem, but not as much as is seen in Mitella stauropetala. The bell-shaped calyx is 1.5-3.5 mm long with oblong to ovate lobes which are white or purplish. The white to purplish-tinged petals are 1.5-2.5 mm long, oblanceolate in shape, and either entire or more commonly with 3 lobes or teeth at the tip. The 5 stamens are shorter than and opposite to the calyx lobes.

Three-tooth mitrewort may be found growing in moist open forests.

Three-tooth mitrewort may be found from British Columbia south through the Cascade and Olympic Mts. to northern California, and east through eastern Washington to Alberta, and hence south in the Rockies to southern Montana. It may also be found in in Grant County and in the Wallowa and Blue Mts..