The 1926 United States Senate election in South Dakota took place on November 2, 1926. Incumbent Republican Senator Peter Norbeck ran for re-election to a second term. In the Republican primary, he faced former State Senator George J. Danforth, who had the support of Governor Carl Gunderson in an intra-party split between Norbeck and Gunderson. Norbeck defeated Danforth by a wide margin, and then faced former State Representative Charles J. Gunderson in the general election. Norbeck defeated Gunderson in a landslide to win re-election.
Former State Representative Charles J. Gunderson won the Democratic nomination unopposed.