Mount Allyn is a mountain with an elevation of 1,125 metres (3,691 ft) AHD that is part of the Allyn Range, located within the Chichester State Forest, in the Upper Hunter region of New South Wales, Australia. Mount Allyn is located about 8 kilometres (5.0 mi) south southwest of Careys Peak and about 50 kilometres (31 mi) northeast of Muswellbrook.
Snow often falls in winter. Much of the mountain is covered in Antarctic Beech cool temperate rainforest.
There is dirt-road access to the peak.