Smith's numbers weren't spectacular on a cold, rainy day. He completed only five of 15 passes for 52 yards with a 7-yard touchdown pass to Washington State's Jason Hill.
But the Heisman Trophy winner made fewer mistakes than Leak, who had a fumble that led to a quick touchdown for the North.
Both Smith and Leak were fighting to improve their standing in a draft that will include Notre Dame quarterback Brady Quinn, who didn't play because of an injury, and LSU's JaMarcus Russell, who was ineligible to play as a junior.
Starting during his last chance to impress NFL scouts in a college game, Smith directed a nine-play, 75-yard opening drive that ended with a 7-yard touchdown run by Penn State's Tony Hunt, who ran for 38 yards on eight carries and was selected the game MVP.
The South had to punt after Leak took a sack for an 8-yard loss. The North answered with a 38-yard field goal by Mason Crosby of Colorado, who capped a 30-yard drive that included Smith's 13-yard completion to Rutgers' Brian Leonard for a first down on fourth-and-7.
Leak, whose Florida Gators demolished Ohio State 41-14 to win the BCS Championship earlier this month, was 5-of-9 passing for 23 yards. UTEP's Jordan Palmer, the brother of the Cincinnati Bengals' Carson Palmer, completed five of eight passes for 91 yards for the South.
With things already going badly, Leak was blindsided by Nebraska's Jay Moore and fumbled at his own 26. The turnover set up a 7-yard TD pass from Michigan State's Drew Stanton to Aundrea Allison of East Carolina.
Crosby added a 21-yard field goal for the North.
Hunt led all rushers followed by Hill, who gained 35 yards on a nifty reverse down the left side that helped set up the North's opening touchdown.
The game was the first shutout in the 58-year history of the Senior Bowl.
Patrick Willis of Ole Miss lead all defenders with 11 tackles and was named the South's defensive player of the game.