Pilosocereus occultiflorus is a tree-like cactus with a woody trunk up to 23 cm in diameter. Often branching meters above the ground, P. occultiflorus is candelabra-shaped and reaches heights of up to 7 meters. The slightly curved stems are dull gray-green, growing up to 3 meters long and 6 to 9.5 centimeters in diameter. On each stem, there are 8 to 9 triangular ribs in cross-section. The areoles on these ribs are spaced 5 to 9 millimeters apart. The spines are yellow, becoming gray with age. The areoles have 6 to 13 central spines and 20 radial spines. A pronounced cephalium is present on mature stems. The floriferous areoles are covered with brown wool. The flowers are 3 to 4 cm long and reach diameters of 2 to 2.5 cm at anthesis. The fruits are 1.9 to 2.4 cm, splitting open when ripe.
The specific epithet "occultiflorus" refers to the flowers hidden in the pseudocephalium. This epithet comes from the latin "occultus" meaning covered or hidden and the latin "florus" meaning flower.