| Election Name: | 1920 United States Senate election in Missouri |
| Country: | Missouri |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1918 United States Senate special election in Missouri |
| Previous Year: | 1918 (special) |
| Next Election: | 1926 United States Senate special election in Missouri |
| Next Year: | 1926 (special) |
| Image1: | Selden Palmer Spencer.jpg |
| Nominee1: | Selden P. Spencer |
| Party1: | Republican Party (US) |
| Popular Vote1: | 711,161 |
| Percentage1: | 53.65% |
| Nominee2: | Breckinridge Long |
| Party2: | Democratic Party (US) |
| Popular Vote2: | 589,498 |
| Percentage2: | 44.47% |
| Map Size: | 270px |
| U.S. senator | |
| Before Election: | Selden P. Spencer |
| Before Party: | Republican Party (US) |
| After Election: | Selden P. Spencer |
| After Party: | Republican Party (US) |
The 1920 United States Senate election in Missouri took place on November 2, 1920 in Missouri. The incumbent Republican Senator, Selden P. Spencer, was re-elected to a full term, having won a special election in 1918. He defeated Breckinridge Long of the Democratic Party. Spencer underperformed Republican presidential nominee Warren G. Harding, who won 54.6% of the vote in the concurrent presidential election.
The Farmer–Worker Party nominated carpenter W. J. Mallett.[3]
The Socialist Labor Party nominated Andrew Trudell.