Boechera breweri is a perennial herb growing from a woody, branching caudex. It produces hairy, erect stems to up to about 20 centimeters tall. There is a basal clump of leaves around the caudex. They are oval-shaped and up to 3 centimeters long. They are coated in forked hairs. There are also a few leaves farther up the plant with bases that clasp the stem.
The flowers have dark purple sepals and lighter purple petals. The fruit is a long, thin, ascending silique up to 6.5 centimeters long. The flowers have thick pinkish-purple sepals and spoon-shaped pink to purple petals.
The fruit is a long, narrow, purple silique which may be many centimeters long.