Agonis theiformis is a species of flowering plant in the family Myrtaceae and is endemic to the southwest of Western Australia.

It is a shrub with elliptic to egg-shaped, sometimes broadly egg-shaped leaves, and clusters of white flowers with mostly 15 to 20 stamens opposite the sepals, the fruit a spherical cluster of cup-shaped capsules.

Flowering mainly occurs from October to December and the fruits are in clusters 6–8 mm (0.24–0.31 in) wide, the individual capsules cup-shaped to broadly top-shaped, 3.5–4.0 mm (0.14–0.16 in) wide.

[2][3] Agonis theiformis was first formally described by Johannes Conrad Schauer in Lehmann's Plantae Preissianae.

[6] This species of Agonis grows in heath, shrubland and forest on a range of soil types from Northcliffe to Cape Riche and inland to the Stirling Range in the Avon Wheatbelt, Esperance Plains, Jarrah Forest and Warren bioregions of southern Western Australia.