Irving had 30 points, 11 assists and four rebounds to snap the Thunder's (33-19) seven-game winning streak. Boston (34-19) has won nine of its last 10 games.
Thunder guard Russell Westbrook had his sixth consecutive triple-double with 22 points, 16 assists and 12 rebounds, but had a costly turnover late in the game.
With 8.1 seconds left in the fourth quarter, Irving caused Westbrook to fumble the ball, which fell into Celtics center Al Horford's hands. Jayson Tatum and Marcus Smart knocked down two free throws each to ice the game.
"Kyrie was great because he kind of got in Westbrook's way and might have even tipped it," Horford told reporters. "That was a big stop for us."
We snagged a huge steal during the final seconds to swing the momentum in our favor before we downed OKC. pic.twitter.com/p7BR7f7TaB— Boston Celtics (@celtics) February 3, 2019
Marcus Morris had 19 points and seven rebounds, and Smart finished with 18 points, seven assists and four rebounds. Tatum scored 11 points and tallied seven rebounds.
Horford notched 17 points and nine assists.
Thunder guard Paul George led the team with a game-high 37 points on 11-of-27 shooting. He added four rebounds and four assists.
Oklahoma City center Steven Adams had 16 points and nine rebounds. Jerami Grant scored 15 points.