The Moonie River is a perennial river of the Barwon catchment within the Murray–Darling basin.
The river was named 'Mooni' by explorer and surveyor Thomas Mitchell on 9 November 1846 but the origins of the name are unknown. In New South Wales, the river is officially known as the 'Mooni River', but common usage uses the same spelling 'Moonie', as in Queensland, where most of the river is located.
The river rises south west of Dalby, near Braemar State Forest, southeast of Tara in Queensland, and flows generally to the south-west, joined by thirteen minor tributaries, before reaching its confluence with the Barwon River, north of the village of Collarenebri, New South Wales, descending 198 metres over its 542 kilometre course.
The catchment area has no major towns and is extremely flat. In the Western Downs Region, the river flows through the town of Flinton and just to the north of Westmar.
