Darren Collison had 16 points and 10 assists, and Roy Hibbert added 14 points and 13 rebounds for the Pacers, who have won five of their past six and ended a nine-game losing streak against the Hawks. The Pacers improved to 20-16 under interim coach Frank Vogel.
It wasn't a sellout, but the crowd of 15,879 was lively in the Pacers' first game since clinching their first playoff berth since 2006.
Atlanta forward Josh Smith missed his second straight game with a sprained right knee.
Indiana shot 49 percent from the field and outrebounded the Hawks 49-36.
The Pacers are averaging 109 points in their past six games. Their latest outburst came two days after scoring 136 against Washington.
Vogel said it was important for his young team to maintain momentum heading into the postseason, so he played his regular rotation, even though Indiana was locked into the No. 8 spot in the Eastern Conference. All three of Indiana's losses to Atlanta had been by double digits.
The Pacers led 56-50 at halftime, then scored the first four points of the second half to go up by 10.
A reverse dunk by Hibbert gave the Pacers a 79-67 lead, and a 3-pointer by Granger pushed it to 13 with a minute left in the third quarter.
Indiana led 82-71 at the end of the period. Granger scored 14 points in the third quarter after scoring nine in the first half.
The Pacers maintained a double-digit lead for most of the fourth quarter. A 3-pointer by Granger and a short jumper by Collison put Indiana up 103-88 with 5 minutes remaining.
Notes: Indiana radio color commentator Bobby "Slick" Leonard returned to broadcasting for the first time since having a heart attack after the Pacers' March 13 game at New York. Leonard, a former Pacers coach, is one of six people whose names are in the rafters at Conseco Fieldhouse.