Styphelia williamsiorum is a species of flowering plant in the heath family Ericaceae and is endemic to a small area in the south-west of Western Australia.

It is a low, compact shrub with decussate, narrowly egg-shaped leaves, and deep purple, tube-shaped flowers with hairy lobes.

[2] Styphelia williamsiorum was first formally described in 2017 by Michael Clyde Hislop and Caroline Puente-Lelièvre in the journal Nuytsia.

[2] This species occurs in the Geraldton Sandplains bioregion of south-western Western Australia from south of Eneabba to Badgingarra and as far east as the Alexander Morrison National Park, where it grows in shallow sandy soil in low heath.

[2][4] Styphelia williamsiorum is listed as "Priority Three" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions,[4] meaning that it is poorly known and known from only a few locations but is not under imminent threat.