Also for the Bulldogs (9-2), which hit three free throws in the final 24 seconds to seal it, Colin Borchert had 11 points. Roquez Johnson and Craig Sword each had 10 for Mississippi State, which will play the winner of Santa Clara-UNLV in Monday's championship game.
South Florida will play the loser of Santa Clara-UNLV in the final round Monday.
The Mississippi State bench outscored the Bulls, 26-9.
After leading 38-35 at halftime, the Bulldogs could not pull away and the Bulls briefly took a 45-44 lead with 15:36 left. Mississippi State later got the lead to 53-47 before the Bulls put together a small rally to tie it, 58-58, with 5:58 remaining. The Bulldogs then scored the next five and never trailed again as Johnson had six points down the stretch.
Mississippi State shot 54 percent from the field in the first half to take a 38-35 halftime lead. South Florida jumped to a 12-5 lead before the Bulldogs led 31-22 with four minutes left. There were four lead changes in the first half.
This is the Bulls' third trip to Las Vegas since 2006. They are 3-2 in Las Vegas since then, all in invitational tournaments.
Mississippi State last played in Las Vegas in the 2001 Las Vegas Classic, going 3-1.
Sunday's meeting was the first between the teams since 1974. Mississippi State was 2-0 all-time against South Florida before Sunday.