Macdonald River, a perennial river that is part of the Namoi catchment within the Murray–Darling basin, is located in the Northern Tablelands district of New South Wales, Australia.

The river rises east of Niangala on the western slopes of the Moonbi Range and the Great Dividing Range and generally flows north west after its confluence with its major tributary, the Cobrabald River, and flows through Warrabah National Park before reaching its mouth, with the Namoi River; dropping 515 metres (1,690 ft) over its course of 169 kilometres (105 mi).

[2] From source to mouth, the river passes through or near the villages of Woolbrook and Bendemeer.

Trout fishing is possible in the waters of the Macdonald River, its creeks and tributaries upstream of the New England Highway road bridge at Bendemeer.

[3] The T A Perry Bridge, that carries the New England Highway and crosses the Macdonald River, was completed in 1985, enabling a bypass of the village of Bendemeer.