Allyn River, a perennial stream of the Hunter River catchment, is located in the Hunter region of New South Wales, Australia.

The Hunter Region, also commonly known as the Hunter Valley, Newcastle Region, or simply Hunter, is a region in northern New South Wales, Australia, extending from approximately 162 km (101 mi) to 310 km (193 mi) north of Sydney. It contains the Hunter River and its tributaries with highland areas to the north and south. Situated at the northern end of the Sydney Basin bioregion, the Hunter Valley is one of the largest river valleys on the NSW coast, and is most commonly known for its wineries and coal industry.