Gerald Green added 18 points for the Rockets, who won both meetings between the teams this season, Sky Sports reported.
Eric Gordon and Austin Rivers added 13 points each for the Rockets, while Clint Capela had nine points and 15 rebounds and Chris Paul had five points, 10 assists and six rebounds.
Kawhi Leonard led Toronto with 26 points, Pascal Siakam had 17 points and 10 rebounds, Danny Green had 14 points and Serge Ibaka had 10 points and 15 rebounds.
The Raptors overcame a 22-point deficit in the second quarter to lead by two points entering the fourth quarter.
The Rockets, held to 14 points in the third quarter, surged to a 10-point lead when Gordon hit a three-pointer with 9:03 to play in the fourth after a Raptors' turnover.
Harden, playing with four fouls, hit a three-pointer with 5:48 remaining and Houston led by 14. Ibaka made two free throws with 4:25 to cut the lead to nine.
Harden's jump shot with 2:54 remaining extended the lead to 13 and ensured there was no way back for Toronto.
Celtics 128 Warriors 95
Gordon Hayward scored 19 of his 30 points in the first half as the Boston Celtics stunned the Golden State Warriors with 73 points in the first 24 minutes en route to a 128-95 shellacking in Oakland.
Kyrie Irving recorded 19 points and 11 assists for the Celtics, who salvaged a season-series split with Golden State after the Warriors took a 115-111 win at Boston in January.
The Celtics were opening a four-game western swing after having lost five of their past six games.
The margin of victory was the Celtics' second-biggest in a road game this season. They trounced the Chicago Bulls 133-77 in December.
Stephen Curry had 23 points while Kevin Durant scored 18 points and DeMarcus Cousins 10 to go with nine rebounds for the Warriors, who suffered their fifth home loss of the season by 20 or more points.
Golden State played without Klay Thompson, who missed his second straight game with a sore right knee.
Jaylen Brown added 18 points, Tatum 17 and Morris 10 for Boston.