The 6-foot-8 forward sat out the last 69 games of the regular season and the first eight of the playoffs.
Haslem subbed in early in the second quarter, but quickly picked up two personal fouls and a technical foul in just three minutes.
In another shift Monday night, Miami center Joel Anthony started for the first time in the postseason. Zydrunas Ilgauskas started the other games, but had just 30 points and 32 rebounds. Anthony had 37 points and 47 rebounds coming off the bench in the five-game series against the Philadelphia 76ers and the first three games against Boston.
Coach Erik Spoelstra made the move after the Celtics won 97-81 on Saturday night to cut the Heat's lead to 2-1.
Information from The Associated Press was used in this report.