Stenanthemum sublineare is a species of flowering plant in the family Rhamnaceae and is endemic to the southwest of Western Australia.

[2][3] Stenanthemum sublineare was first formally described in 2001 by Barbara Lynette Rye in the journal Nuytsia from specimens collected near Bullsbrook in 1997.

[4] The specific epithet (sublineare) means "almost linear", referring to the leaves.

[2] This species grows in woodland, dominated by Banksia attenuata, and is only known from the Swan Coastal Plain near Bullsbrook.

[2][3][5] Stenanthemum sublineare is listed as "Priority Two" by the Western Australian Government Department of Biodiversity, Conservation and Attractions,[5] meaning that it is poorly known and from only one or a few locations.