Monvillea amazonica is a species of cactus (family Cactaceae) found in Peru and Bolivia.
Monvillea amazonica is at first erect, many meters long, and minimally branched. Stems have 7 acute ribs and areoles are long. Each areole has about 15 weak spines that are long. The floriferous region is on the upper part of the stem but not at the tip. Flowers are straight and are also long. The fruit is oblong and capped by the withering flower.