The species is sometimes confused with G. canescens, which has similarly cut leaves, but these are usually more markedly discolorous than those of G. harveyi, and the indumentum is thinner (the leaf blade is often visible through the hairs on the lower surface in G. canescens; it is completely obscured in G. harveyi). Also, G. canescens always has gland-tipped hairs on the upper parts (they are very rare in G. harveyi, and then confined to the pedicels and lower part of the sepals), and the petals are usually white (rarely flushed pink), not deep pink nor purple, 8-11.5 x 4-5 mm, not 12-15 x 6.5-9 mm. The two species are allopatric.
Many-stemmed, clump-forming perennial herb, stems spreading, decumbent or suberect, slender, becoming woody in lower parts, young parts with silvery retrorse appressed hairs. Stipules deeply dissected, segments linear-acuminate. Leaves all cauline, petioles long, all but the uppermost much longer than the blade, with silvery retrorse appressed hairs, blade ±5-30 mm diam., digitately (3-)5-lobed almost or quite to the base, each lobe rhomboid in outline, deeply pinnatifid, the segments oblong-lanceolate, entire or the largest with an occasional tooth, appressed silvery-sericeous above, more densely so below. Peduncles opposite the uppermost leaves and much exceeding them, with silvery retrorse appressed hairs, 1- or 2-flowered. Pedicels seldom exceeding 50 mm, hairy as the peduncles, and occasionally with a few spreading gland-tipped hairs below the calyx. Sepals 5.5-6(-8) x 2.5(-3.5) mm excluding mucro, appressed silvery-sericeous, occasionally with a few gland-tipped hairs at the base. Petals 12-15 x 6.5-9 mm, obovate, shallowly notched, magenta or purple-blue. Rostrum with somewhat spreading hairs.
Geranium harveyi is found on the mountains of the central and eastern Cape, from the Nieuweveld Mountains north of Beaufort West east to the Stormberg and the mountains near Cala in neighbouring Transkei, the mountains around Queenstown and the Windvogelberg at Cathcart, and south to Boschberg at Somerset East.