Grevillea oligantha is a shrub of the genus Grevillea native to an area in the southern Wheatbelt, Great Southern and south-western Goldfields-Esperance regions of Western Australia. The many branched shrub typically grows to a height of 0.3 to 2.5 metres (1 to 8 ft) and has non-glaucous branchlets. It has simple undissected flat obovate leaves with a blade that is 25 to 70 millimetres (1.0 to 2.8 in) in length and 5 to 10 mm (0.20 to 0.39 in) wide. It blooms from May To November and produces a terminal or axillary raceme irregular inflorescence with yellow, orange or brown flowers. Later it forms warty ellipsoidal or ovoid glabrous fruit that is 10 to 12 mm (0.4 to 0.5 in) long.