Pelargonium tetragonum is a plant adapted to grow in dry habitats (xerophyte). It branches from the base and if supported by other vegetation, will reach a height of 2 m. The plant tends to sprawl, but can be successfully grown as a pot specimen. Pelargonium tetragonum is distinguished by its almost leafless, three- to four-angled, jointed and succulent stems. When present, the leaves are fleshy, palm-shaped and sometimes have red zonal markings.

The very attractive cream to pink flowers occur in pairs on the flower stem. Each flower has four petals, with the upper two significantly larger than the lower pair. The large upper petals are streaked with red. The flowering time is from September to December.