Bolstered by the return of Marcus Smart and Al Horford, who both missed Tuesday’s 118-107 drubbing, Boston were a team transformed as they squared the best-of-seven series 1-1, AFP reported.
But the Celtics shrugged off the misfiring Game 1 performance in emphatic fashion, draining 20-of-40 from beyond the arc to overwhelm Miami.
Tatum led the scorers but there were huge contributions throughout the Celtics lineup.
Smart finished with 24 points, 12 assists and nine rebounds, while Jaylen Brown also posted 24 points, including 12 from three-point range.
Grant Williams added 19 from the bench, while Horford and Payton Pritchard had 10 points each.
Jimmy Butler led the Miami scoring with 29 points but only three other Heat players made double figures.
Smart put the seal on a devastating first-half display with a pullup jump shot to make it 70-45 at half-time.
Miami rallied late in the third quarter and cut the Boston lead to 17 points at one stage, but the Celtics regrouped and again pulled away.
A three-pointer from Tatum took them 25 points clear in the closing seconds of the third quarter at 94-69, a lead which they held going into the final quarter.
Smart made it a 30-point lead early in the fourth, bamboozling the Miami defense to drain a superb stepback three-pointer from 26 feet as Boston closed out a brutal victory.
Game 3 in the series takes place in Boston today.