The 2004 United States Senate election in Hawaii took place on November 2, 2004 alongside other elections to the United States Senate in other states as well as elections to the United States House of Representatives and various state and local elections. Incumbent Democrat U.S. Senator Daniel Inouye won re-election to an eighth term.
Inouye won every single county with at least 70% of the vote. His best performance was in Kauai County, where he won with an estimated 80%; also was Cavasso's weakest performance, getting just 16.5% of the vote there.