| Election Name: | 1934 United States Senate election in Washington |
| Country: | Washington |
| Flag Image: | Flag of Washington (1923–1967).svg |
| Type: | Presidential |
| Ongoing: | no |
| Previous Election: | 1928 United States Senate election in Washington |
| Previous Year: | 1928 |
| Next Election: | 1940 United States Senate election in Washington |
| Next Year: | 1940 |
| Election Date: | November 6, 1934 |
| Image1: | File:Lewis B. Schwellenbach, 1940.jpg |
| Nominee1: | Lewis Schwellenbach |
| Party1: | Democratic Party (United States) |
| Popular Vote1: | 302,606 |
| Percentage1: | 60.93% |
| Nominee2: | Reno Odlin |
| Party2: | Republican Party (United States) |
| Popular Vote2: | 168,994 |
| Percentage2: | 34.02% |
| Map Size: | 270px |
| U.S. Senator | |
| Before Election: | Clarence Dill |
| Before Party: | Democratic Party (US) |
| After Election: | Lewis Schwellenbach |
| After Party: | Democratic Party (US) |
The 1934 United States Senate election in Washington was held on November 6, 1934. Incumbent Democrat Clarence Dill did not run for a third term in office. He was succeeded by Democrat Lewis Schwellenbach, who defeated Republican Reno Odlin for the open seat.