Acacia acanthaster is a shrub belonging to the genus Acacia and the subgenus Phyllodineae. It is native to an area in the Great Southern and Goldfields-Esperance regions of Western Australia. The prostrate, sprawling and spiny shrub typically grows to a height of 0.1 to 0.6 metres (0 to 2 ft) and a width of 1.5 metres (5 ft). It blooms from August to October and produces yellow flowers.