Corryocactus serpens is a sparsely branched, shrubby cactus with stems, which are initially upright, become creeping and trailing, reaching lengths of 2 to 3 meters and a diameter of. These stems have a green epidermis. Ribs on the stems number 4 to 6 and are obtuse. Areoles on these ribs bear 6 to 12 needle-like, straight, brown spines, each measuring long. The carmine redflowers are up to long and wide. The olive green fruits are approximately long and up to in diameter.