The Cowboys (11-4, 1-2) also snapped a 10-game losing streak against the Cyclones (9-5, 0-3).
Donovan Jackson went 6-of-8 from beyond the arc and finished with a career-high 30 points for Iowa State.
Carroll hit a 3-pointer and the Cowboys led 87-85 with 1:40 left in the extra period. Nick Weiler-Babb, who finished with 12 points, tied the game with a pair of free throws on the next possession.
Oklahoma State then got some cushion, making it 91-87 on four straight points from Cameron McGriff. Smith then iced the game by making three free-throws in the final 32 seconds.
Solomon Young finished with 12 points and freshman Cameron Lard matched a season-high with four blocks for the Cyclones.
Mitchell Solomon added 14 points for Oklahoma State.
Iowa State finished the first half on a 17-2 run and led 34-32 at the break. However, Oklahoma State did much better handling the Cyclones pressure and scored the opening eight points of the second half, pushing to a 40-34 lead on a layup by Tavarius Shine, who finished with 15 points.
Iowa State answered when Lindell Wigginton was fouled converting a layup and he made the ensuing free throw to give his team a 49-48 lead with 10:58 left in the game.
The Cowboys showed they were equally as battle-tested. A 3-pointer by Carroll and free throw by Shine gave them a 52-51 margin with just under 10 minutes left.
Jackson made a 3-pointer and Iowa State made of 6 of 7 shots to take a 72-66 lead with just under five minutes left.
Oklahoma State would not go away and a 3-point play by Brandon Averette and layup by Smith pulled the Cowboys to within 76-75 with two minutes remaining. A pair of free throws by Carroll on the next possession provided Oklahoma State with a 77-76 lead with 1:21 left.
Hans Brase made a short jumper for Iowa State, which then forced a turnover. After Jackson made one of two free throws, the Cowboys tied the game 79-79 on a jumper by Smith to force overtime.
--Field Level Media
Iowa State | Oklahoma State | |
Donovan Jackson 30 | Scoring | Jeffrey Carroll 24 |
Nick Weiler-Babb 11 | Assists | Kendall Smith 5 |
Nick Weiler-Babb 9 | Rebounds | Mitchell Solomon 9 |
Donovan Jackson 8 | Free Throws Made | Tavarius Shine 6 |
Nick Weiler-Babb 2 | Steals | Jeffrey Carroll 2 |
Cameron Lard 4 | Blocks | Tavarius Shine 2 |
Team | Points | FG% | 3PM-3PA | FTM-FTA | Assists | Rebounds | Blocks | Steals | Turnovers |
Iowa State | 87 | 40.6 | 6-18 | 25-30 | 16 | 37 | 5 | 6 | 15 |
Oklahoma State | 96 | 46.5 | 6-20 | 24-31 | 18 | 38 | 6 | 5 | 13 |