Hawes hit a 3-pointer, then a driving layup for a 109-108 lead with 2:01 left.
James blew two consecutive chances to put Miami up, losing the ball on a drive down the middle, then missed a 6-footer on the next possession.
Shane Battier missed his seventh straight 3-point attempt, and the Sixers put the game away from the free-throw line.
LeBron James had 25 points for Miami.
• Allen Iverson officially retired from the NBA on Wednesday, ending a 15-year career during which he won the 2001 MVP award and four scoring titles. Iverson retired in Philadelphia where he had his greatest successes and led the franchise to the 2001 NBA finals.
Iverson says he’ll be a Sixer “until the day I die.”
The 6-foot guard had not played in an NBA game since Feb. 20, 2010, and had a brief pro stint in Turkey.
CAVALIERS: Center Andrew Bynum, who missed all of last season for Philadelphia with knee problems, played in his first game in 17 months.
Bynum’s appearance was a mild surprise. He only received medical clearance to play a few hours before the game. The 7-footer, finished with three points, three rebounds, two assists and one block.