The Pacers improved to 4-0 at home for the first time since going 7-0 to start the 2002-03 season.
They led by as many as 24 points and snapped Atlanta's three-game winning streak, sending the Hawks home with their first loss since a triple-overtime thriller against Miami last week.
The Hawks will start a four-game homestand Thursday against Charlotte. The Pacers are in Toronto on Friday and play just three of their next 12 games at home.
Atlanta erased an 11-point deficit in the second quarter, taking a 50-49 lead on Jeff Teague's layup inside of a minute.
But the Pacers scored the next three points for a 53-50 halftime advantage, starting a 22-4 run that bled into the third quarter and gave them a 71-54 lead on Granger's layup.
Jeff Foster, Indiana's 6-foot-11 big man off the bench, knocked down his first three-pointer since 2008 at the buzzer to make it 80-59 heading into the fourth quarter and the game was never in doubt down the stretch.
Atlanta's Jason Collins was ejected from the game with 3.5 seconds left for a flagrant 2 foul after roughing up Lou Amundson near the bucket as the Indiana player went up for a shot.
Earlier, the Pacers led by as many as nine and shot 57.1 percent in the first quarter to carry a 28-20 lead into the second.
Atlanta had been 11-4 in the previous 15 meetings between the teams, including 9-2 in the last 11...Tracy McGrady (back spasms) missed the game for the Hawks.