The Gamecocks, who beat St. Joseph's in the final last year, can become the second team to win consecutive NIT crowns with a win over Michigan on Thursday night. The Wolverines beat Old Dominion 66-43 in the other semifinal Tuesday night.
Tarence Kinsey added 21 points and Brandon Wallace 19 for the Gamecocks (22-15).
Trailing 42-32 at halftime, Louisville (21-13) got within 48-41 early in the second half as freshman Terrence Williams scored seven straight points, but South Carolina answered with a 10-1 run to take a 58-42 lead with 11:35 to play. Balkman and Wallace had acrobatic dunks during the spurt.
Louisville scored the next eight points to close the gap to 58-50, but Balkman scored six straight to put the game away.
South Carolina shot a blistering 60 percent from the field with most of its baskets coming on layups and dunks.
Taquan Dean scored 21 points for Louisville and finished 12th on the school's all-time scoring list with 1,649 points. Williams added 16 for the Cardinals, who fell to 0-3 at Madison Square Garden this season. The Cardinals lost to St. John's in the regular season and Pittsburgh in the opening round of the Big East tournament.
The Gamecocks, who advanced to the semifinals with a 65-62 victory at Cincinnati, closed out the first half with a 14-4 run. With the game tied at 28, Balkman started the run with a two-handed dunk and capped it with a three-point play with 2.1 seconds left. He finished the first half with 11 points on 5-for-6 shooting.