Grevillea marriottii is a shrub of the genus Grevillea native to a small area in the Wheatbelt region of Western Australia. The open, multi-stemmed and lignotuberous shrub typically grows to a height of 0.8 to 1.2 metres (3 to 4 ft) and has non-glaucous branchlets. It has simple linear tripartite leaves with a blade that is 15 to 40 millimetres (0.6 to 1.6 in) in length and 1.5 to 3.5 mm (0.06 to 0.14 in) wide. It blooms from July to October and produces a terminal raceme irregular inflorescence with green, white or green flowers. Later it forms ribbed ellispoidal glabrous fruit that is 10 to 14 mm (0.4 to 0.6 in).