Blunt finished the night with 55 percent of the vote to 44 percent for Carnahan, the daughter of the late Gov. Mel Carnahan, NBC News reported.
Democratic Rep. Ike Skelton, chairman of the House Armed Services committee, lost in a close fight with former state Rep. Vicky Hartzler. Hartzler won the state's 4th District seat with 113,500 votes to Skelton's 101,507.
Rep. Russ Carnahan, brother of the defeated Senate candidate, won over his Republican opponent in the suburban St. Louis 3rd District.
Carnahan had 99,011 votes to Ed Martin's 95,593.