Thomasia sarotes is a species of flowering plant in the family Malvaceae.

It is an upright, spreading shrub with purple, pink to mauve or white flowers and is endemic to the south-west of Western Australia.

The flowers are borne in groups of 2 to 5 on the ends of branches or in upper leaf axils on a peduncle about 20 mm (0.79 in) long, each flower on a pendent pedicel 4–6 mm (0.16–0.24 in) long with linear bracteoles at the base.

The flowers are about 15 mm (0.59 in) in diameter, the sepals purple, pink to mauve or white, and the petals tiny.

[6] This thomasia grows in clay, sand, granitic and rocky soils on low ridges and dunes in the Avon Wheatbelt, Coolgardie and Mallee.