The 1916 United States Senate election in California was held on November 6, 1916. Incumbent Senator John Downey Works did not run for re-election.
Governor of California and 1912 Progressive Party vice presidential nominee Hiram Johnson won the open seat, defeating Democratic attorney and Mayor of San Marino George Patton.
Primaries
Republican primary
Candidates
Willis H. Booth, banker and philanthropist
Hiram Johnson, Governor of California
Results
Democratic primary
Candidates
George S. Patton, Mayor of San Marino
Results
George Patton was unopposed on the ballot, but Hiram Johnson, Willis Booth, and Walter Thomas Mills received write-in votes.
Progressive primary
Candidates
Hiram Johnson, Governor of California
Results
Gov. Hiram Johnson was unopposed on the primary ballot, but Willis Booth did receive write-in votes.
Socialist primary
Candidates
Walter Thomas Mills
Results
Walter Thomas Mills was unopposed on the primary ballot, but Hiram Johnson and Willis Booth received write-in votes.
Prohibition primary
Candidates
Marshall W. Atwood, perennial candidate
Results
Atwood was unopposed on the primary ballot, but Hiram Johnson and Willis Booth received write-in votes.