Acacia semitrullata is a shrub of the genus Acacia and the subgenus Phyllodineae. It is native to a small area in the South West region of Western Australia. The slender, erect and pungent shrub typically grows to a height of 0.2 to 0.7 metres (0.7 to 2.3 ft). It blooms from May to October and produces cream-white flowers.