Pelargonium magenteum becomes a spreading woody shrub of 1 m tall and larger in width. It is a reseeder, not a resprouter, being single-stemmed. It is known in Afrikaans as the persmalva (purple pelargonium).
The species distribution is in the northwest of the Western Cape and the southwest of the Northern Cape in Namaqualand, the western Karoo and the Little Karoo, from Nieuwoudtville to Calitzdorp.
The habitat is rocky slopes and outcrops. The species is not considered to be threatened in its habitat early in the twenty first century (Vlok and Schutte-Vlok, 2015; Manning and Goldblatt, 1997; Bond and Goldblatt, 1984; iNaturalist; http://redlist.sanbi.org).