Acacia hopperiana is a small tree or shrub belonging to the genus Acacia and the subgenus Juliflorae that is endemic to western Australia. The shrub or occasionally a tree typically grows to a height of 0.6 to 4 metres (2 to 13 ft) and has smooth grey bark. It often has a dense habit with red-brown coloured glabrous branchlets that are silvery between the fine ribs. The terete, pungent, light green phyllodes are 6 to 14 cm (2.4 to 5.5 in) in length and 0.7 to 1 mm (0.028 to 0.039 in) wide. The phyllodes are sub-rigid and straight to shallowly incurved with ten longitudinal nerves of uniform width which are each separated by a narrow dark longitudinal furrow. It blooms in August producing yellow flowers. The simple inflorescences are made of flower-spikes that are 10 to 25 mm (0.39 to 0.98