One Nation has secured its first lower house seat in Western Australia, winning the Secret Harbour electorate in a by-election held on August 29. The victory marks a significant breakthrough for the party, which has traditionally been a minor player in Australian politics, and signals a potential shift in voter sentiment across the state and beyond.

Luke Herdegen, a gym owner who relocated to Western Australia three years ago, captured the seat, which had been held by Labor since 1989. Labor’s vote collapsed by more than 22 percentage points from the previous state election, dropping from around 46.5 percent to approximately 24 percent in primary votes, while the Liberal Party’s share also fell, from about 25 percent to 17 percent. Herdegen won about 39 percent of the primary vote and secured victory after preferences, with a final two-party-preferred vote of 57 percent.

The result has sent ripples through both major parties. Labor Premier Roger Cook acknowledged the challenge posed by One Nation’s surge, stating that the outcome underscored the importance of politicians maintaining close ties with their communities. Cook rejected suggestions that his own seat of Kwinana, adjacent to Secret Harbour, was at risk but admitted the by-election demonstrated One Nation’s growing appeal.

One Nation leader Pauline Hanson celebrated the win as evidence that no Labor seat is guaranteed, emphasizing the party’s expanding influence in what she described as new "heartland" areas in Perth’s southern suburbs. Herdegen indicated plans to target neighboring Labor-held electorates such as Kwinana, Baldivis, and Rockingham, which have traditionally been considered secure for Labor.

The Liberal Party experienced a notable decline in support in Secret Harbour, further complicating its position. Liberal leader Basil Zempilas downplayed his party’s performance, arguing that Labor’s loss in its stronghold was the more significant development. The result also raised concerns for Liberal federal MP Andrew Hastie, whose seat of Canning overlaps with the area and who faces a divided conservative vote amid One Nation’s rise.

Political analysts note that One Nation’s breakthrough reflects broader voter dissatisfaction with established parties, particularly in working-class communities. The party’s focus on issues such as immigration, cost of living, and opposition to certain cultural and environmental policies resonates with constituents who feel overlooked by metropolitan political elites. This trend parallels right-wing populist movements in several Western democracies, where similar parties have made gains among voters disillusioned with traditional politics.

Despite its historic win in Western Australia, One Nation’s challenge to the two-party dominance remains uncertain. Major parties still maintain organisational advantages and experience, but this result adds momentum to the view that Australian politics is undergoing increasing fragmentation. The upcoming Victorian state election, scheduled in three months, will further test One Nation’s growing influence.