| Election Name: | 1865 United States Senate election in California |
| Type: | presidential |
| Ongoing: | no |
| Flag Image: | First Bear Flag of California (1846).svgborder |
| Previous Election: | 1861 United States Senate election in California |
| Previous Year: | 1861 |
| Next Election: | 1871 United States Senate election in California |
| Next Year: | 1871 |
| Election Date: | December 16, 1865 |
| Votes For Election: | Majority vote of both houses needed to win |
| 1Blank: | Joint session |
| 2Blank: | Percentage |
| Image1: | Cornelius Cole, Los Angeles, 1920s 3x4.jpg |
| Nominee1: | Cornelius Cole |
| Party1: | National Union Party (United States) |
| 1Data1: | 92 |
| 2Data1: | 77.31% |
| Nominee2: | William T. Coleman |
| Party2: | Democratic Party (United States) |
| 1Data2: | 26 |
| 2Data2: | 21.85% |
| Senator | |
| Before Election: | James A. McDougall |
| Before Party: | Democratic Party (United States) |
| After Election: | Cornelius Cole |
| After Party: | National Union Party (United States) |
The 1865 United States Senate election in California was held on December 16, 1865, by the California State Legislature to elect a U.S. Senator (Class 3) to represent the State of California in the United States Senate. In a special joint session, former Republican Congressman Cornelius Cole was elected over former Democratic State Assemblyman William Tell Coleman.[1] Cole was the candidate of the Union Party.[2]