Coccinia rehmannii is a slender perennial, creeper or climber, arising from a large tuberous rootstock, almost glabrous to rather densely hairy, becoming smooth whitish and speckled at maturity, especially in drier areas. The simple tendrils enable the vine to grow over and smother vegetation, cover fences and power lines, trees, shrubs and walls. It can grow up to 4 m high. The plant has perennial roots, woody at the base producing hypocotyl (carrot-like) tubers, that grow up to 0.5 m deep.
 
The leaves of C. rehmanni are simple, alternate, and paired, with a tendril on each node, except for the first nodes. The leaves are 20–80 × 25–130 mm, usually distinctly petiolate. Young leaves tend to be shallowly lobed. Upper leaf surface more or less densely white, pustulate. Lower leaf surface glabrous, sometimes wart-like; the leaf margin usually beset conspicuously with small teeth and often bears trichomes.