It is an erect or sprawling shrub to about 2 m (6 ft 7 in) high, with red to orange or yellow flowers in spring.

Gastrolobium leakeanum was described by James Drummond as being "twelve to fifteen feet (3.7–4.6m) high with opposite leaves three inches long (76mm) by two broad (51mm) and bears clusters of large deep scarlet flowers in the axils of the leaves".

[3] The species was subsequently described in William Hooker's Journal of Botany and Kew Garden Miscellany.

[4] Mountain pea grows on mountaintops, ridges and steep slopes in sandy clay or loam over quartzite or in stony soils.

[6] This species is classified as "Priority Two" by the Western Australian Government Department of Parks and Wildlife[6] meaning that it is poorly known and from only one or a few locations.