Lechenaultia macrantha is a species of low growing plant found on sandy or gravelly soils in Western Australia.
The species, when viewed from above, has a wreath-like form during its flowering period around August to November. The prostrate habit of Lechenaultia macrantha is between fifty and one hundred and fifty millimetres in height and spreading out to one metre. The branches are fleshy, the leaves are narrow, linear, and up to forty millimetres in length. The large yellow, pink, red flowers are arranged at the terminus of branches in a ring. The diameter of the five petals is between thirty and thirty five millimetres.
The distribution of the species is the Geraldton Sandplains and Avon Wheatbelt regions in the southwest of the state, extending inland to the Eremaean Botanical Province.
Lechenaultia macrantha is placed in the family Goodeniaceae, nearly all of which are found in Australia's arid regions. The species was first described, by Kurt Krause in 1912, using the synonymous genus name Leschenaultia, names that commemorate Jean Baptiste Leschenault de la Tour. Lechenaultia macrantha is given an epithet derived from Greek that refers to its large flower. A common name for the plant is Wreath lechenaultia.
The plant is cultivated as an ornamental, most easily by propagation of cuttings.