Oklahoma City led by 27 in the second quarter and 22 in the third, but had to put its starters back on the floor midway through the fourth after Orlando pulled within four.
The Thunder held the Magic scoreless over the final 2 1/2 minutes and closed with an 8-0 run to improve to 30-4 at home this season.
"We knew going into this game Orlando would play hard and they've been doing that all year," Thunder coach Scott Brooks said. "They are a team that is going to be good in the future very quickly. Our focus was inconsistent throughout the game. We pride ourselves in being more focused in every game and every possession and it wasn't the case tonight."
The focus was there in the first half.
The Thunder scored a season-high 73 points in the first two quarters, shooting 64 percent from the floor and converting 18-of-22 free throws to lead by 17 at the break.
Jameer Nelson led Orlando with 26 points, hitting 5-of-12 three-pointers, including a crucial one with 3:37 left to pull the Magic to 106-102.
Durant had a three-point play 18 seconds later to push the lead back to seven. Tobias Harris' layup got the Magic within five with 2:34 remaining, but they didn't score again.
Westbrook made his third 3-pointer of the night with 2:07 to go, Thabo Sefolosha hit a free throw, Durant made two from the line and added a layup in the final minute to close the scoring
"We made plays on both ends," Durant said of the fourth quarter. "We passed the ball and made some shots in the fourth. It was a disappointing effort in the third but I liked the way we finished."
The Thunder looked like they were going to put the game away early, shooting 71 percent in the first quarter to lead by 13. They extended the lead to 27 before the Magic pulled to 73-56 at the half.
Oklahoma City dominated the Magic in nearly every statistical category, outrebounding Orlando 52-33 -- including 44-26 on the defensive end.
"Just great concentration level in the second half for us to be down 27 and cut the lead to four," Orlando coach Jacque Vaughn said. "Their two best players made two 3s, daggers that pushed the lead a little bit but overall just really good things especially in the second half."
With his team struggling to find the 20-win mark, the Magic's first-year coach acknowledged Orlando (18-48) was playing more for pride than a chance at the playoffs.
The second-half rally where Orlando outscored Oklahoma City 48-44 was a start. The Magic began cutting into the lead, outscoring the Thunder 28-22 in the third.
"We just didn't play with the focus we needed," Brooks said. "We missed too many free throws, layups and missed opportunities. Those are things we have to get better at."
Durant said the Thunder, who improved to 49-17, forgot what made them so successful in the first half.
"Guys weren't worried about shooting the ball (in the first half)," Durant said. "We were worrying about passing and finding the open shot. The second half the ball got sticky. We've got to stay disciplined throughout the whole game."
Harris continued to be a bright spot for the Magic since being acquired from Milwaukee. He scored 19 points in 40 minutes while largely guarding either Westbrook or Durant.
Ibaka scored 20 and Kevin Martin added 15 off the bench for the Thunder, who have won two in a row and 10 of their last 13.
Oklahoma City F Hasheem Thabeet did not play due to a sore back. Rookie Perry Jones was the beneficiary of the available minutes, scoring eight points and grabbing five rebounds in 11:14 of work. ... Oklahoma had seven more turnovers than the Magic and half as many steals (6). ... Each team had 56 points in the paint. ... Harris scored in double figures in five of his 28 games with the Bucks. Since arriving in Orlando, he's scored double digits in nine of 11 games.