Williams was an electoral district of the Legislative Assembly in the Australian state of Western Australia from 1890 to 1950.

In 1898, it included the towns of Bannister, Narrogin, Darkan, Arthur River, Wagin, Katanning, Woodanilling, and Moojebing.

His actions brought about the downfall of the Labor government of John Scaddan in August 1916 when it next met.

Johnston briefly served as Speaker in February 1917, however, his former Labor colleagues opposed his appointment and refused to respect his authority, forcing him to resign after just a few days in favour of James Gardiner.

Sitting member Victor Doney of the Country Party transferred to the new Narrogin seat.