The R40 is a provincial route in South Africa that connects the Eswatini border at Bulembu via Barberton, Mbombela, Bushbuckridge, Acornhoek and Hoedspruit with Phalaborwa.

It reaches a junction with the main east–west street of Mbombela (R104 road; Samora Machel Drive) west of the CBD before crossing over the Crocodile River to enter Riverside.

Midway through the town centre, the R40 meets the R538 and turns north to be co-signed with it through the Kingsview suburb as Theo Kleynhans Street.

At this intersection, the R40 turns north and enters the town of Hazyview, where it meets the R536 road before crossing the Sabie River.

Changing direction to the north-east, it eventually crosses the Ga-Selati River and after a short distance, the R40's northern terminus is a t-junction with the R71 road, 5 kilometres west of Phalaborwa.