Harris, acquired earlier in February in a deal with the Los Angeles Clippers, posted his highest point total in eight games with the 76ers. The 76ers needed his offense because center Joel Embiid, the league’s No. 6 scorer, missed his fourth straight game with left knee soreness.
Simmons finished with 11 points, 13 rebounds and 11 assists for his ninth triple-double of the season.
Russell Westbrook posted his 25th triple-double of the season with 23 points, 11 rebounds and 11 assists, but he made 8 of 24 shots. Jerami Grant added 23 points for the Thunder, who lost their third straight.
Thunder forward Paul George, the league’s No. 2 scorer, sat out with soreness in his right shoulder. Thunder coach Billy Donovan said before the game that George was injured during a loss at Denver on Tuesday night.
The 76ers led by 16 in the first half and were up 60-49 at the break. The Thunder cut their deficit down to two late in the third, but the 76ers handled the surge and led 86-79 heading into the fourth.
The 76ers led by two with 2.1 seconds left and barely got the ball inbounds. JJ Redick made two free throws with 1.5 seconds remaining to put the game out of reach.
76ers: Grant, who started his career in Philadelphia, made 10 of 17 shots and had six rebounds. … Jonah Bolden, a rookie from Australia, matched a season high with 14 points on 6-of-7 shooting.
Thunder: Free agent pickup Markieff Morris got his first start with the Thunder. It was just his fourth game with Oklahoma City. He finished with 17 points in 19 minutes. … It was the 129th triple-double of Westbrook’s career.
76ers: Host the Golden State Warriors on Saturday.
Thunder: Visit the San Antonio Spurs on Saturday.