Ibaka started after missing the first two games of the series. The Thunder had said he likely would miss the rest of the playoffs, but the team changed course Friday.
Manu Ginobili scored 23 points and Tim Duncan added 16 points and eight rebounds for the Spurs.
Game 4 is Tuesday night at Oklahoma City.
Ibaka, who also had seven rebounds and four blocks, pointed to the sky as he left the game to cheers with 3:17 remaining and the Thunder ahead by 20 points.
The Thunder outrebounded the Spurs 52-36 after losing the battle of the boards in the first two games. San Antonio, which shot at least 50 percent in the first two games, shot just 40 percent on Sunday night.
San Antonio won the first two games by a combined 52 points, but things were different from the start with Ibaka's return. Thunder coach Scott Brooks also inserted speedy Reggie Jackson into the starting lineup in Thabo Sefolosha's place. Jackson finished with 15 points.
The crowd roared when Ibaka's name was announced during pregame introductions, and it got even louder when he started playing. He had eight points, three rebounds and two blocks in just over six minutes of play in the first quarter.
Twice in the final minute of the first half, Ginobili hit 3-pointers, and both times, Westbrook answered with a 3-pointer. The last one, with 0.6 seconds left, gave the Thunder a 57-53 lead. Oklahoma City shot 56 percent in the first half, but turned the ball over 12 times. Ginobili had 20 points and made 5 of 7 3-pointers before the break to keep the Spurs close.
Oklahoma City extended its lead to 83-76 at the end of the third quarter. A runner by Durant, then a 3-pointer by Caron Butler pushed the Thunder lead to 90-76 with just over 10 minutes to play.
Notes: Thunder C Kendrick Perkins picked up his third foul eight minutes into the game. He played just 13 minutes and finished with four points and three rebounds. Backup center Steven Adams, a rookie, had seven points and nine rebounds. ... Thunder G Derek Fisher took a hit and was bleeding from the top of his head in the first quarter. He got six stitches. ... The Thunder shot 63 percent from the field in the first quarter but trailed 29-28 at the end of the period. ... Westbrook was issued a technical foul in the first quarter. ... Ginobili scored just three points in the second half.