Baylor recovered the ensuing onside kick and ran out the clock to secure its third straight victory.
Cowboys coach Mike Gundy insisted there were no lingering effects after the tough loss to the Sooners.
"I would hate to hang my hat on that," Gundy said. "I do not think there was a hangover. If there was, that was my fault because that is my responsibility."
Florence threw a 75-yard touchdown pass to Tevin Reese and the senior quarterback also rushed for 71 yards and a score in the final home game of his career.
Florence has thrown for 4,121 yards this season and is 172 yards shy of breaking the school's single-season passing mark, which Robert Griffin III set last season.
"To be playing our best ball at the end of year is what you want to do," Florence said. "We want to carry on the streak and get to eight wins. We're hot right now and our goal is stay hot."
The Bears took the lead for good early on Lackey's second interception return for a touchdown in two games.
The junior linebacker picked off a short pass in the flat and ran untouched for a 26-yard touchdown that gave Baylor a 10-3 lead with 7:58 remaining in the first quarter.
The Bears scored on their next two possessions to build a 24-3 lead. Glasco Martin powered in for a 2-yard touchdown run to cap a 16-play, 98-yard drive.
Florence then found Reese for a 75-yard touchdown pass. Reese caught the ball at the 40 and raced past three Oklahoma State defenders into the end zone.
The Cowboys got within 24-17 with consecutive touchdowns. Walsh had a 1-yard run and Chelf threw a 15-yard scoring pass to Stewart.
Chelf was 30 of 51 for 333 yards with two touchdowns and two interceptions.
Florence's 3-yard touchdown run made it 31-17 with 3:33 left in the first half.
Oklahoma State tight end Blake Jackson dropped two potential touchdown passes in the game. He had one on the Cowboys' first drive of the game and again early in the third quarter.
The Cowboys were able to kick field goals after the drops, including Quinn Sharp's 43-yarder in the third quarter that made it 31-20.