Pilosocereus gaumeri is a slender-growing branchingcactus up to about tall. It has green to yellowish green stems with 8–13 ribs. The areoles are about across and have up to 15rigidspines. The spines are up to long and yellow to brown when fresh. Flowering areoles have dense tufts of silky hairs up to long. Non-flowering areoles have few or no silky hairs. The flowers are long, occasionally up to long. The outer segments are reddish green. The inner segments are white to yellowish green. The flowers last for one night. The fruits have purple pulp when ripe.