Carter contributed 17 points and Matt Barnes had 14 for the Southeast Division-leading Magic (50-21), who won 50 games in three straight seasons for the first time since 1993-96. The Magic have won three straight and 10 of 11. Mickael Pietrus and Jason Williams had 10 apiece.
"I've never won 50 games before," Carter said. "It's pretty cool. I'm thinking of the bigger picture. I want to win a championship."
Howard was 9-for-11 from the field in his league-leading 55th double-double for Orlando, which has won seven consecutive regular-season games against the Sixers.
"That's a great honor to win 50 games," Howard said. "It's tough to do. We've been consistent, and we're going to keep going and become one of the elite teams."
Andre Iguodala and Elton Brand led the Sixers with 23 points apiece, while Samuel Dalembert had 16 points and 14 rebounds. The Sixers have dropped three in a row and fell to 11-24 at home. They own the third-fewest home wins in the league behind only Minnesota (nine) and New Jersey (three).
"We played well," Brand said. "I'm tired of playing well. We want to win the game."
Philadelphia got within 71-67 with 4:46 left in the third quarter before the Magic pulled away thanks to their deft 3-point shooting against the worst 3-point defensive team in the league.
Seven different Magic players connected on at least one 3-pointer, with Barnes going 4-for-4. Orlando was 16-for-31 from beyond the arc.
"That's what they do," Sixers coach Eddie Jordan said. "They do it to everybody. It's not like we had major breakdowns on our 3-point defense."
After a dunk by Iguodala closed the gap to 93-84, the Magic quickly responded with a running hook shot by Howard and a 3-pointer by J.J. Redick for a 98-84 advantage with 6:14 remaining.
Philadelphia never got closer than eight the rest of the game.
"We did a good job closing it out," Orlando coach Stan Van Gundy said.
Howard had 13 points and 10 rebounds at halftime as the Magic jumped out to a 56-47 advantage. Orlando shot 53 percent from the field and was 7-of-12 from 3-point territory.
Forward Thaddeus Young (right thumb fracture) and guard Lou Williams (back) sat out for the Sixers. Forward Jason Kapono started for the first time this season for Philadelphia. ... Pietrus was questionable with a sprained left ankle, but came off the bench in the second quarter.