| Election Name: | 1921 Western Australian state election |
| Country: | Western Australia |
| Type: | parliamentary |
| Ongoing: | no |
| Previous Election: | 1917 Western Australian state election |
| Previous Year: | 1917 |
| Next Election: | 1924 Western Australian state election |
| Next Year: | 1924 |
| Seats For Election: | All 50 seats in the Western Australian Legislative Assembly |
| Election Date: | 12 March 1921 |
| Leader1: | Philip Collier |
| Leader Since1: | 16 April 1917 |
| Party1: | Australian Labor Party (Western Australian Branch) |
| Leaders Seat1: | Boulder |
| Percentage1: | 36.81% |
| Swing1: | 11.99 |
| Last Election1: | 15 seats |
| Seats1: | 17 seats |
| Seat Change1: | 2 |
| Leader2: | Tom Harrison |
| Leader Since2: | 30 July 1919 |
| Party2: | Country Party (Western Australia) |
| Leaders Seat2: | Avon |
| Percentage2: | 17.78% |
| Swing2: | 1.28 |
| Last Election2: | 12 seats |
| Seats2: | 16 seats |
| Seat Change2: | 4 |
| Leader3: | James Mitchell |
| Leader Since3: | 17 May 1919 |
| Party3: | Nationalist Party (Australia) |
| Leaders Seat3: | Northam |
| Percentage3: | 27.73% |
| Swing3: | 7.12 |
| Last Election3: | 16 seats |
| Seats3: | 10 seats |
| Seat Change3: | 6 |
| Premier | |
| Before Election: | James Mitchell |
| Before Party: | Nationalist Party (Australia) |
| After Election: | James Mitchell |
| After Party: | Nationalist Party (Australia) |
Elections were held in the state of Western Australia on 12 March 1921 to elect all 50 members to the Legislative Assembly. The incumbent government, led by Premier James Mitchell of the Nationalist Party and supported by the Country Party and National Labor Party, won a second term in government against the Labor Party opposition, led by Opposition Leader Philip Collier.
At this election Edith Cowan became the first woman elected to any Australian parliament.
See also: Results of the Western Australian state election, 1921 (Legislative Assembly).
|}
164,688 electors were enrolled to vote at the election, but 6 of the 50 seats were uncontested, with 17,740 electors enrolled in those seats. Of these, 3 were held by Labor, 2 by the Country Party and 1 was held by the National Labor Party.