Rodney Purvis had 16 points and T.J. Warren added 15 points for the Wolfpack (3-1), who shot only 28.6 percent from the field.
''We have to come out and have a better start,'' Purvis said. ''But that won't happen anymore. This can happen any night. We have a bull's-eye on our back. We have to prepare ourselves physically and mentally for every game and come out here and play.''
Smart was the tournament MVP.
"You could tell when we first scored, they didn't have a feeling of intensity by the looks on their faces,'' he said. ''They have a lot of great players. And we just knew we were gonna have to come out, be ready and play hard. I could feel it. I could sense I was hot and my teammates got me the ball and it got us going."
''Marcus (Smart) just got hot and got into a rhythm,'' Oklahoma State coach Travis Ford said. ''He can do so many different things on the court to help us win. And LeBryan Nash played with such a flow throughout the tournament and it was just fun to watch. They did so many different things well. We are at our best when LeBryan is getting to the foul line.
He was joined by Nash, Warren, Tennessee's Jarnell Stokes and Akron's Zeke Marshall on the all-tournament team.
''I thought we played against three teams in this tournament that will be in the NCAA tournament in Akron, Tennessee and NC State, Ford said.
''The way we started the game was the difference. We played with a high level of intensity, playing above the rim and taking them out the areas where they like to score. N.C. State might have the most potent offense we will see all year. Their top six guys can score in so many different ways. N.C. State is one of the top teams in America and we competed with them in every aspect.''
Smart had a pair of 3-pointers early, part of an 8-2 run in the first half that gave the Cowboys a 13-9 lead.
Smart finished with 18 points in the first half as the Cowboys led 38-28 at the break.
Nash took over the scoring load for Oklahoma State in second half. He scored 17 second-half points. Forte added 3 3-pointers in the second half.
He had a dunk and two free throws to make it 42-28.
Nash added a layup with 14:25 left to give the Cowboys a 15-point lead at 48-33.
Smart had a layup with 6:25 remaining to cap a 14-5 run and give Oklahoma State a 65-55 lead.
"You gotta give Oklahoma State credit.'' N.C. State coach Mark Gottfried said. ''I thought they played pretty well. That was as poor a performance as we have had in a long time. I'm not sure we did a lot of things well. We came out casual and, like in a prize fight, they took it to us.
''It's my job to make sure we are ready to play. Tonight, we weren't ready to play. It's disappointing. We were playing for the championship of this tournament and came out very casual to start the game. I didn't like that at all. We didn't seem to make shots. We struggled to make baskets.''