Garnett has missed 21 of the team's last 25 games with a strained right knee.
Spokesman Jeff Twiss said Monday that Boston coach Doc Rivers decided there was no point to bring back Garnett for two essentially meaningless games.
The Celtics are in Philadelphia, where they will play the 76ers on Tuesday night. They return to Boston on Wednesday to close out the regular season against the Washington Wizards.
Twiss also said that reserve forward Leon Powe could return for one or both of the final regular-season games after missing the last 12 with a right knee injury.