Grevillea haplantha is a shrub of the genus Grevillea native to a large area in the Wheatbelt and Goldfields-Esperance regions of Western Australia. The erect or spreading shrub typically grows to a height of 0.5 to 3 metres (2 to 10 ft) and has non-glaucous branchlets. It has simple flat linear undissected leaves with a blade that is 20 to 85 millimetres (1 to 3 in) in length and 1.5 to 2 mm (0.06 to 0.08 in) wide. It blooms from May to December and produces an axillary raceme irregular inflorescence with red or pink flowers. Later it forms an ellipsoidal ribbed or ridged hairy fruit that is 10 to 13 mm (0.4 to 0.5 in).