The Avon River, a perennial river of the Hawkesbury-Nepean catchment, is located in the Southern Highlands and Macarthur districts of New South Wales, Australia.

The Avon River rises on the western slopes of the Illawarra escarpment, near Calderwood within the Wollongong local government area and flows generally north, reaching its confluence with the Cordeaux River, south of Wilton.

The river descends 155 metres (509 ft) over its 32-kilometre (20 mi) course.

[1] The river is impounded by Lake Avon, the largest of the four reservoirs within the Upper Nepean Scheme that supplies potable water for greater metropolitan Sydney.

Located near Bargo, approximately 100 kilometres (62 mi) south-west of Sydney,[2] construction of Avon Dam commenced in 1921 and was completed in 1927.