The sophomore forward missed the Wolfpack's first three games this season because of a suspension for accepting $410 in impermissible benefits.
He made his first seven shots from the field as the Wolfpack stayed even with the Commodores.
With about 6 minutes left he started cramping and he spent the rest of the game on the floor next to the bench being treated by trainers.
"I thought in the first half he was exceptional but he got tired," North Carolina State coach Mark Gottfried said. "It's one thing to practice every day and another to being in game shape. He started cramping late and he was playing well when he started cramping. He was really good early."
Leslie averaged 11.0 points as a freshman and he had that many in the first 10½ minutes of his first game as a sophomore.
Gottfried said it will take some time for the team and Leslie to be in sync.
"It's tough. The tricky part is we played well without him," Gottfried said of the 2-0 start. "I know we need him. He's got to kind of be integrated without breaking stride of the other guys. He needs to adapt to us as much as we have to adapt to him. It's good to have him back though, because he's an athletic guy who makes us play different on the floor."
John Jenkins scored 28 points for the Commodores, who closed the game on a 10-2 run. Jenkins, who missed the Commodores' last game with a sprained right ankle, had 20 points in the first half. The junior guard wasn't even sure about playing Saturday night until the morning shootaround.
"The ankle really wasn't an issue. I did feel a little better at the shootaround," Jenkins said. "I was going to go tonight no matter what. I wasn't letting my teammates down. But I never thought I'd be this productive. Coach got in my face a little in the shootaround, because I thought I wouldn't feel good at all. But once I started shooting, I felt better."
Vanderbilt coach Kevin Stallings told Jenkins to stop worrying about his injury.
"This morning, he said his foot was hurting again and he was shooting and missing," Stallings said. "I told him that he was thinking too much about his foot and I said something to remind him."
The Commodores will play the winner of the Texas-Oregon State game for the championship on Monday night at the Izod Center.
Saturday night's game was close on the scoreboard and stat sheet until Vanderbilt (3-1) took the lead for good with the deciding spurt that started with 2:16 to play.
Jeffrey Taylor added 17 points for Vanderbilt and Lance Goulbourne had 15, including 10 in the opening 7 minutes of the second half.
"We're happy to win, but we have a long way to go before we're a good team," Taylor said. "We're going to do our best to be the team we want to be."
The Commodores were picked No. 7 in The Associated Press' preseason Top 25 and they fell to 18th after a loss to Cleveland State.
Vanderbilt is still without Festus Ezeli, whose sprained right knee is expected to keep him out about another month.
"We don't have Festus. It's foolish for us to sit around and wait for him to show up. We're not going to moan and complain," Stallings said. "We have what we have. When and if we get him back, we'll be a different team. But he's not here. He won't be here Monday and if we sit around and wait for him to come back, we're going to be in trouble."
Richard Howell had 16 points and nine rebounds for the Wolfpack (2-1).
DeShawn Painter's reverse layup with 2:43 left gave North Carolina State a 77-76 lead.
Taylor's tip-in with 2:16 to go started the closing run. After Lorenzo Brown missed a 3-point attempt for the Wolfpack, Jenkins hit a step-back 3 and North Carolina State never seemed to recover. Goulbourne made two free throws and Taylor added one after a steal by Goulbourne and it was 84-77 with 26 seconds to play.
"I thought Vandy showed late in the game that they had experience," Gottfried said. "I know that team very well and that was the difference, their experience. I thought we competed. I liked the effort we got from our guys."
Vanderbilt shot 51.9 percent for the game (28 of 54), while the Wolfpack went 31 of 62 (50 percent). Vanderbilt had a 36-34 advantage on the boards. The only big difference in the box score was Vanderbilt going 9 of 25 from 3-point range (Jenkins was 4 of 9) as the Wolfpack went 4 of 11.