The incumbent Labor Government, led by Premier Mark McGowan, won a second consecutive four-year term in office in a historic landslide victory.

ABC News psephologist Antony Green called the election for the Labor Party 42 minutes after the polls closed, with 0.7% of the vote counted.

[5] Labor's unprecedented victory extended to the Legislative Council, and the party claimed a majority of the seats in the upper house for the first time.

Opinion polls pegged the McGowan Government as unbackable favourites for a second term, and suggested that Labor would be re-elected by a record majority.

Labor enjoyed support approaching 70% in the two-party preferred polls, and McGowan maintained a personal approval rating of 88%.

Election dates are set in statute with four-year fixed terms, to be held on the second Saturday of March every four years.

[20] Key dates for the election are:[21] In January 2021, Liberal Party candidate for Victoria Park Amanda-Sue Markham defended her husband's controversial views on homosexuality and conversion therapy.

[42] In March 2021, One Nation dumped Roger Barnett as its candidate for the seat of Forrestfield after offensive Muslim and Aboriginal comments emerged from his Facebook page that were posted between 2012 and 2018.

This does not necessarily imply a causal relationship but rather some similarities between electoral districts which moved more or less towards the Labor party on the two-party-preferred.

[53] Electoral districts with a high proportion of persons aged 60 years or older swung less to Labor than the rest of the state (R2 = 0.2, p < 0.001), even after adjusting for the incumbency effect mentioned above.

[53] Electoral districts with a high proportion of persons working in clerical or administrative jobs swung more to Labor than the rest of the state (R2 = 0.12, p < 0.01).

[53] Electorates with a higher proportion of persons who spoke a language other than English at home also somewhat swung more to Labor than the rest of the state (R2 = 0.08, p < 0.05).