Garnett finished with 12 points and 11 rebounds while Brandon Bass contributed 14 points as the Celtics outscored the Bulls 30-20 in the final frame to pull out the victory.
Boston used a tough defense to limit Chicago to 36.5 percent shooting as its racked up its eighth win in nine games.
Chicago got 12 points from Marco Belinelli in stumbling to its fourth loss in five contests.
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