Leader of the Opposition (Western Australia)

In the Australian state of Western Australia, the leader of the opposition is the leader of the largest minority political party or coalition of parties in the Legislative Assembly of the Parliament of Western Australia. By convention, the leader is generally a member of the Legislative Assembly.

Prior to 1911, the Western Australian political system had neither organised political parties (apart from the Labor Party) nor an organised opposition. The notion of leader of the opposition was well understood, however, and on occasions was applied to members. Maitland Brown, for example, was often referred to as "Leader of the Opposition" during his period as an outspoken critic of Governor Robinson's Government.

In the 2025 state election, the Liberal Party held seven seats against the National Party's six and became the official Opposition of the state. Accordingly, the leader of the Liberal Party, Basil Zempilas also gained the official title of Leader of the Opposition after he was elected as party leader on 25 March 2025.