Harden had 26 points, 10 rebounds and 10 assists in three quarters for his second career triple-double as Houston picked up its fifth consecutive victory.
The 76ers (15-57) stuck around early before a big second-quarter run allowed the Rockets to pull away and roll to the win.
Philadelphia matched the 2010-11 Cleveland Cavaliers for the NBA's worst skid and can set the record at home against Detroit on Saturday.
James Anderson led the 76ers with 30 points. He made six three-pointers.
Portland 100, at Atlanta 85: LaMarcus Aldridge had 25 points and 16 rebounds in his return from a back injury, and the Trail Blazers ended a three-game losing streak.
Damian Lillard added 21 points for the Trail Blazers, who had lost seven of 10 and were in danger of falling out of the fifth spot in the Western Conference playoff standings.
The Hawks have lost five in a row, all without Kyle Korver, who has been struggling with back spasms. They lead the Knicks by 1 1/2 games in the race for the eighth and final playoff spot in the Eastern Conference.
Jeff Teague, who was scoreless in Wednesday night's loss at Minnesota, led the Hawks with 22 points. Lou Williams had 16 points, including 13 in the final period when Atlanta closed the deficit to six points.