Australia's far-right One Nation party has claimed a decisive victory in the Secret Harbour state byelection in Western Australia, defeating Labor in a seat the party had previously held comfortably. One Nation's Luke Herdegen beat Labor's Georgia Tree by 57% to 43% after preferences, with nearly all votes counted — a dramatic reversal from Labor's 61.5–38.5 win over the Liberals in the same seat at the 2025 state election. One Nation recorded a primary vote of 39.1%, a swing of more than 30 percentage points toward the party since that election, while Labor's primary vote collapsed by more than 22 points to just 24.4%. The Liberals, who had run a distant third with 17.3% of the primary vote, saw their preferences split relatively evenly between the two leading parties, a dynamic that analysts warn could limit One Nation's ability to convert strong primary support into seats at future general elections.

Secret Harbour is a beachside suburban electorate on Perth's southern coastal fringe, home to many working-class and mortgage-belt voters with vocational rather than university qualifications and low ethnic diversity — demographics in which One Nation has consistently performed strongly. The byelection was triggered after senior Labor minister Paul Papalia retired midterm. WA Premier Roger Cook had acknowledged before polling day that holding the seat would be a battle, given that byelections often disadvantage the incumbent party, particularly one commanding as large a majority as Labor's 46 of 59 lower house seats won in 2025.

One Nation leader Pauline Hanson declared the result reflected