Miami completed a two-game, regular-season sweep of the Mavericks, the team that defeated the Heat in last year's championship series. Miami's other win over Dallas this season came on the opening day of the campaign, on the day the Mavericks raised their championship banner.
James played despite suffering a dislocated finger Monday against Indiana. He added five assists and two steals.
Dwyane Wade and Udonis Haslem each produced 16 points for the Heat, who had lost two in a row.