Prostanthera tallowa is a species of flowering plant in the family Lamiaceae and is endemic to the Kangaroo Valley area of New South Wales.

It is an erect, aromatic shrub with narrow egg-shaped to linear leaves and mauve to light purple flowers with darker dots inside the petal tube.

The flowers are arranged in bunches of ten to twenty near the ends of branches, with bracteoles 4–5 mm (0.16–0.20 in) long at the base of the sepals.

[2][3] Prostanthera tallowa was first formally described in 2012 by Barry Conn and Trevor Wilson in the journal Telopea from specimens collected in Morton National Park near Tallowa Dam in 1988.

[2][4] This mintbush is only known from near the type location where it grows in open Eucalyptus forest on rocky soils derived from sandstone.