The Heat lead the best-of-seven East semifinals 3-2, with Game 6 in Indiana on Thursday night.
James added 10 rebounds and eight assists. Shane Battier scored 13 points, Mario Chalmers had eight points and 11 rebounds, and Udonis Haslem finished with 10 points for Miami, which never trailed.
Paul George scored 11 points for Indiana, with starting forwards Danny Granger and David West adding 10 points apiece. Granger left with a sprained left ankle in the third quarter, and West left with what the Pacers called a left knee sprain at the end of that period.
Miami shot a franchise playoff-record 61 per cent, best of any team in the playoffs this season. It was an 11-point game when Granger departed early in the third quarter, and the Heat outscored the Pacers by 21 the rest of the way.