Kemba Walker scored 36 points, with 18 coming in the fourth quarter which saw the Hornets fight back from an 18-point deficit to clinch victory.
The defeat was the third in a row for the Celtics, who went into the game hoping to clinch their place in the post season.
But while their play-off spot is virtually assured, the Hornets are facing an uphill struggle to finish in the top eight in the Eastern Conference.
Despite Saturday's victory, they remain two-and-a-half games behind eighth-placed Miami as the Heat beat the Washington Wizards 113-108 on the back of 20 points from Dwyane Wade.
Elsewhere, Luka Doncic clinched a triple-double with 23 points, 11 rebounds and 10 assists as the Dallas Mavericks thrashed the Golden State Warriors 126-91.
The feat takes the 20-year-old fourth on the all-time NBA list for most triple-doubles by a rookie.
In the absence of Stephen Curry, the Warriors fell to their biggest home loss this season which saw the reigning champions slip behind the Denver Nuggets in the race for top spot in the Western Conference.
The Philadelphia 76ers saw their six-game winning streak come to an end as Trae Young inspired the Atlanta Hawks to a 129-127 victory.
Rookie Young scored 32 points, with his last two coming with 0.01 seconds left on the clock and giving Atlanta victory.
The Sacramento Kings maintained their slim hopes of a play-off spot in the west by beating the Phoenix Suns 112-103 while the Utah Jazz moved a step closer to clinching their place in the post season with a 114-83 thrashing of the Chicago Bulls.
Elsewhere, the Portland Trail Blazers secured their third win in a row with a 117-112 victory against the Detroit Pistons while the Minnesota Timberwolves stopped a five-game losing run with a 112-99 success against the Memphis Grizzlies.