The Boomi River, an anabranch of the Barwon River and part of the Macintyre catchment within the Murray–Darling basin, is located in the north–western slopes region of New South Wales, flowing downstream into the South Downs region of Queensland, Australia.
The river rises about 15 kilometres east of Gundabloui, and flows generally north–east, joined by five minor tributaries, before reaching its confluence with the Macintyre River, about 12 kilometres north–east of Boomi. The river descends 40 metres over its 231-kilometre course.
The Boomi River flows past, but not through, the town of Mungindi.
