The Thornybush Nature Reserve is a private nature reserve in Limpopo / Mpumalanga that shares an unfenced border with the Timbavati Private Nature Reserve. It thus forms part of the Greater Kruger National Park, an open conservation area that measures approximately 7 000 000 hectares or 23 000 square kilometres.

The reserve can be described as a keystone reserve within the greater Kruger National Park.

The seasonal Timbavati River flows into the Reserve from the south-east whilst the Monwana River, a large tributary of the Klaserie, flows in from the north of the reserve with the smaller Mozambange entering from the west.

Thornybush is situated entirely in the Savanna Biome. The larger part of the reserve is classified as Granite Lowveld with a small area of the Phalaborwa-Timbavati Mopaneveld present in the north.

Granite Lowveld is a threatened vegetation type and because of the protection of this Thornybush makes a significant contribution to the achievement of provincial and natural biodiversity. The reserve contains both deciduous and evergreen trees and is characterised by a diversity of habitat from north to south, a distance of approximately 25km.

Dominated by Combretum and Acacias, the lush and diverse vegetation encourages the existence of a vast array of fauna, including Lion, Leopard, Elephant, Buffalo and both species of Rhino as well as Cheetah and Wild Dog in addition to the wide variety of antelope, whilst over 364 species of birds have been identified and verified on the reserve of which 11 are listed as threatened.

The Reserve is easily accessible by air with twice-daily flights from Johannesburg and Cape Town landing at the nearby Eastgate Airport. Transfers from Eastgate are less than an hour's drive away from the reserve.