He drained both from the line to put OKC up three, with Houston turning the ball over on their final posession, leaving George to ice the game at the free throw line.
Westbrook scored 21 points, 12 rebounds and 11 assists in the win but shot just 8-of-21 from the field and 1-of-5 from 3-point range as his field-goal percentage on the season dropped to 41.5.
Paul George led all scorers with 45 points (12-22 FG, 6-14 3pt FG), 11 rebounds and 3 assists for the Thunder, while Russell Westbrook secured his 22nd triple-double of the season (9th consecutive, tying Wilt Chamberlain for the longest such streak in National Basketball Association history) and 126th of his career with 21 points, 12 rebounds and 11 assists.
Harden and George traded buckets down the stretch and after Westbrook's layup gave the Thunder the lead with 26.9 seconds left, Harden missed a 3-pointer, with George fouled as he got the rebound with 3.4 seconds left. The Thunder posted a 53-39 edge on the glass.
Two remarkable streaks were extended here on Saturday, with James Harden scoring at least 30 points in his 29th consecutive game and Russell Westbrook recording a triple-double in his ninth straight game.
The Thunder were up by three points at that point, so the intervention prevented the Rockets from getting up a potential game-tying three-point shot.
Chris Paul almost posted a triple-double (18 points, 10 rebounds, nine assists) in his strongest performance since his return from a hamstring injury.
Oklahoma matched the Rockets' 42-point second quarter with their own 42-point period in the third.
In the din of a prime-time rally against the Houston Rockets on Saturday night, the Thunder point guard was having what passes for a quiet moment.
OKC started the game slow, commiting 11 turnovers in the first half, which led to 17 Rockets points as Houston took a comfortable 22-point half-time lead.
But it was George's work on defence in combination with his Thunder team-mate Russell Westbrook which received specific praise from their coach.
Paul George continued his sensational season posting 45 points on 12-22 shooting and 6-14 from three to propel himself into the top tier of MVP conversations now.
The last 12 minutes was everything a fan could want.