Mimulus breweri is a species of monkeyflower known by the common name Brewer's monkeyflower. It is native to western North America from British Columbia to California to Colorado, where it grows in moist spots in several habitat types. This is a hairy annual herb producing a thin, erect stem up to 21 centimeters tall. The herbage is reddish green in color. The paired opposite leaves are linear in shape and up to 3.5 centimeters long.