Carter, who joined the Magic in the offseason, shone in a defensive battle between two of the top sides in the Eastern Conference.
Orlando scored the game’s final five points after Carter’s turnaround jumper with 2:32 remaining broke a 78-78 tie.
“I enjoy playing big games. I live for it,” Carter told reporters after attempting a season-high 29 shots. “We really respect (the Celtics), they’re one of the best. We’re trying to get there consistently and prove ourselves in the same way.”
Paul Pierce scored 21 points for Boston, who shot 34 percent from the field and lost for the third time in four games.
The Celtics were trying to earn a measure of revenge against the Magic, who eliminated them from last year’s playoffs in seven games when Kevin Garnett was sidelined with a knee injury.
With Garnett now returned to health and Boston having made key acquisitions, including forward Rasheed Wallace, the team is looking to return to the form that earned them an NBA championship in 2008.
After reaching the NBA Finals a year ago, the Magic have also made personnel changes, starting with a trade for Carter. The eight-time All-Star has helped Orlando start the year at 10-3 despite team-wide injuries.
Against the Celtics, Orlando used a 15-2 run in the first quarter to establish early control of the game.
Ray Allen tallied nine of his 15 points in the second, where Boston pulled closer to trail 43-40 at halftime before the Magic again claimed the momentum in the second half.
Rashard Lewis contributed 16 points in his third game since serving a 10-game suspension for taking a banned substance and Mickael Pietrus added 14 for Orlando.
The Magic were without starting point guard Jameer Nelson who will miss 4-6 weeks following knee surgery yet still managed their fourth straight win.
The Celtics struggled from behind the arc making just 2-of-19 three-point attempts as they fell to 9-4.
“We’re not a team that takes losing well,” Garnett said. “We’re still trying to figure it out.”
