The Rockets outscored Philadelphia 53-31 after the game was tied midway through the third period.
Harden was 7-of-12 from the field and missed just once in 18 free throw attempts for 33 points.
Jeremy Lin added 18 points and six assists while Omer Asik had 17 points and 15 rebounds. Houston won for the fourth time in five contests and moved one game above the .500 mark.
Houston went on a 17-8 run to end the third period and the 76ers came no closer than seven points in the final quarter.
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