Pelargonium greytonense is a much branched, erect shrub growing to about 1 m in height. It is sometimes aromatic although not always. Older stems become woody and covered in fine hairs, some of these hairs being glandular.

The typical three leaf lobes are triangularly arranged and heart-shaped and roughly dentate. Leaf surfaces are uneven, being slightly folded along the veining. Flowers appear in groups of two to nine. They are white to pale pink. The upper two petals have dark red markings. The lower three are unmarked and much narrower.

The species has much unevenness of characteristics as is common in young species. It is thought to have originated as a natural hybrid between P. hermanniifolium and P. papilionaceum. The distribution is limited to the Riviersonderend Mountains; the plants are common near the town of Greyton. The habitat is sheltered fynbos ravines (Lalli, 2005 Witwatersrand University; wiredspace.wits.ac.za; Van der Walt, 1984; irapl.altervista.org).