Even before completing their fourth straight victory, the Cavaliers were assured of the division title thanks to Chicago’s loss to Orlando.
They also secured the second seed behind Atlanta in the Eastern Conference playoffs.
James finished with 21 points, nine rebounds and eight assists, while Kyrie Irving led the Cavaliers with 27 points.
Kevin Love added 16 points and 11 rebounds for the Cavs, who earned their first Central Division title since 2009-2010 — before James departed his home state team for four seasons in Miami.
“It means a lot,” said James, who returned to Cleveland this season as a free agent.
“Just from the simple fact that I understand how hard it is to win in professional sports and to be able to clinch a division and put a banner in our building it means something to me and it should mean something to all of us.
“We understand we have bigger goals than this, but along with bigger goals you have accomplishments you can’t take for granted.”
Although the Hawks are already assured of the top seed in the East, they’re making a strong run into the playoffs.
Al Horford scored 24 points, including a dunk with 19 seconds left that lifted Atlanta to a 114-111 victory at the Brooklyn Nets on Wednesday.
The defeat saw the Nets fall into a tie with Boston for seventh place in the Eastern Conference, with the Celtics owning the tiebreaker.
If the Nets can hang on for the eighth and final playoff spot in the East they would face the Hawks in the first round.
The Celtics inched closer to a playoff berth with a 113-103 victory over Detroit, but Miami and Indiana are just one game back in the race for the final post-season spot.
In the Western Conference, reigning NBA champions San Antonio continued their bid to grab the Southwest Division with a 110-98 victory over division leaders Houston.
Tony Parker led the Spurs with 27 points. Kawhi Leonard chipped in 20 points and Boris Diaw added 15 points and nine rebounds off the bench for San Antonio, who have won nine straight and pulled within one half-game of the Rockets and Memphis Grizzlies for the division lead.
Memphis parlayed an impressive shooting performance into a 110-74 victory over the New Orleans Pelicans.
The Grizzlies shot 51.1 percent from the floor overall. Six Memphis players scored in double figures, with Zach Randolph, Marc Gasol and Jeff Green scoring 15 apiece.
The Pelicans lost for the second time in three games and dropped into a tie for eighth in the Western Conference with idle Oklahoma City.