The Nuggets (14-17) dropped their eighth straight game.
This game was basically over at intermission. That's when the Sixers built a 68-56 halftime lead after 13 lead changes and eight ties. It was their highest first-half point total of the season.
They accomplished the feat by shooting 64 percent from the floor in the second quarter.
Defensively, the Sixers held the Nuggets to 39.3 percent shooting in the decisive quarter.
"I thought our bench came in and did a great job," coach Brett Brown said. "The things we're trying to do on defense slowly took its toll and enabled us to get out and run and gave us a little bit of an edge.
"I feel like the second period got us rolling through our defense and our second group."
The reserves provided the defensive spark and the starters lit up Denver in the second quarter.
Evan Turner scored seven of his game-high 23 points in the quarter. The swingman wasn't even the team's most dominant player in the period.
Rookie point guard Michael Carter-Williams scored nine of his 16 points in the quarter. Power forward Thaddeus Young tallied eight of his 17. He also finished with 10 rebounds. Shooting guard Hollis Thompson scored seven of his 11 points in the quarter.
The Nuggets pulled within 86-79 on Anthony Randolph's foul shot with 2 minutes, 15 seconds left in the third.
But the Sixers responded with a 9-0 run to take a 95-79 lead with 27.9 seconds left in the quarter.
Shortly after that, things turned into a circus for the Nuggets.
Some of the fans started heading for the doors at the conclusion of the quarter. Then fans started pouring out and booing after James Anderson's reserve layup gave the Sixers a 104-89 lead with 5:33 left.
Former Sixer Andre Miller had to be restrained on the Nuggets bench during the timeout moments after Anderson's basket.
"Terrible, terrible performance by our team," Denver coach Brian Shaw said. "It's not even a slump right now. It's worse than a slump."
The Sixers, on the other hand, are enjoying their first winning streak since beating Miami, Washington and Chicago at the start of the season.
"You hope things slowly come together," Brown said. "You hope you just stay the course, and you don't blink. . . . I'm happy for them. The defensive side is where I'm most pleased."