Smart scored 30 points, and the Cowboys nearly blew a big lead before beating Purdue 97-87 on Thursday in the opening round of the Old Spice Classic.
Markel Brown added 25 points for the Cowboys (6-0), who came in averaging 100.2 points and had defeated their first five opponents by an average of 37.8.
Oklahoma State led 52-29 at halftime after going to the foul line 25 times.
''I'm glad that we won,'' Oklahoma State coach Travis Ford said. ''We're happy with the win and we'll move on. It wasn't the prettiest thing. It's not the way you actually draw it up. It's great learning lesson for us. Teams are going to make runs.''
Smart, an AP preseason All-American, spent considerable time on the bench in the second half with four fouls when the game tightened up.
''It was devastating to see that I wasn't out there to help my team out,'' Smart said. ''Purdue was coming. They were making a run. I'm very proud of my teammates.''
Purdue (5-1) got 18 points from Bryson Scott, and Errick Peck added 12. Ronnie Johnson, who was averaging 13.8 points, struggled with foul trouble and had 10 points.
''We slowed things down and we ran Purdue's offense in the second half,'' Scott said. ''First half, guys like me, I was forcing a lot of shots. Doing a lot selfish things. Second half, we came out and played as a team and we were able to chop the lead down.''
The Boilermakers stormed back late and pulled within 84-80 on a 3-pointer by Kendall Stephens with 3 minutes left. Brown and Smart made layups to give Oklahoma State a little breathing room.
''I told our team, as many things as I'm not happy about, I'm very happy with the last three or four minutes,'' Ford said. ''We very easily could have come up on the other end of the stick.''
Johnson didn't get his first points until making a basket a minute into the second half.
The Cowboys went ahead 67-46 with 14 minutes left on a pair of dunks by Brian Williams. This is the first time Oklahoma State has scored 90 or more points in six consecutive games.
Smart, who scored 24 before halftime, received a technical after reacting to a foul call against him midway through the second half.
Johnson and Brown were both given technicals during a brief scrum later in the half. Purdue's Jay Simpson was called for a flagrant foul and ejected late in the first half.
''I thought who we are as a team was shown in both halves,'' Purdue coach Matt Painter said. ''You saw an immature team in the first half not really handle coaching. Our guys, I think their ego clashed with reality in the first half. Anytime you face someone who's got a lot of attention, who's ranked high, you want to go right at them and you want to beat them by yourself, and you can't beat Oklahoma State by yourself. You've got to beat them as a team.''