Mpumalanga lies in eastern South Africa, north of KwaZulu-Natal and bordering Swaziland and Mozambique. It constitutes 6.5% of South Africa's land area. In the north it borders on Limpopo, to the west Gauteng, to the southwest the Free State and to the south KwaZulu-Natal. The capital is Nelspruit. Prior to 1994, Mpumalanga was part of Transvaal Province.

The Drakensberg Escarpment divides Mpumalanga into a westerly half consisting mainly of high-altitude grassland called the Highveld and an eastern half situated in low altitude subtropical Lowveld/Bushveld, mostly savanna habitat. The southern half of the Kruger National Park is situated in the latter region. The Drakensberg exceeds heights of 2000m in most places with this central region of Mpumalanga being very mountainous. These regions have alpine grasslands and small pockets of Afromontane Forest. The Lowveld is relatively flat with interspersed rocky outcrops. The Lebombo Mountains form a low range in the far east forming the border with Mozambique.

Some of the oldest rocks on earth are to be found in the Barberton area and these ancient greenstones and metamorphosed granites form the Crocodile River Mountains in the south-east of the province.