The Lakers' Kobe Bryant addressed the crowd prior to the game, paying tribute to Jerry Buss.
Buss died earlier this week at the age of 80, having been the owner of the Lakers' franchise for the last 34 years. A memorial service will be held for Buss on Thursday.
Howard scored 24 points and grabbed 12 rebounds to lead the Lakers, who built an 18-point lead during the second half.
Bryant added 16 points and Antawn Jamison had 15. Los Angeles hit half its field goal attempts with Howard going 10-for-13.
Paul Pierce scored 26 for the Celtics, who have lost the opening two contests in a five-game road trip.