The 1925 United States Senate election in Wisconsin was held on September 29, 1925, to complete the unexpired term of U.S. Senator
Robert La Follette, who died on June 18.
The seat was won by La Follette's son and personal secretary,
Robert M. La Follette Jr. over mostly Republican opposition. He defeated three candidates in the Republican primary and overcame a challenge from fellow Republican
Edward F. Dithmar, running on a "Coolidge & Dawes Platform" ticket.