The Bulls were able to snap a five-game losing streak while handing the Mavericks a 13th loss in their last 16 games.
After scoring the game's first 10 points, the Mavericks led until a layup by Portis drew the Bulls even at 96-all with 4:09 remaining. His subsequent short jumper and another layup gave Chicago its first advantage of the game.
Kris Dunn and Lauri Markkanen bombed in late 3-pointers as the Bulls, who had lost 13 of their previous 15 games, were able to pull away.
Portis continued a recent scoring flurry with a team-high 22 points for the Bulls, who completed a season-series sweep of the Mavericks. Chicago had won 127-124 at Dallas in January.
The 23-year-old reserve has scored in double figures in 11 straight games, a stretch that includes a 38-point explosion against Philadelphia.
Dunn had 18 points and a game-high seven assists, and Zach LaVine added 16 points for the Bulls while both Markkanen (17 points, game-high 12 rebounds) and David Nwaba (10 points, 11 rebounds) recorded double-doubles.
The Bulls outshot the Mavericks 47.2 percent to 41.7.
Harrison Barnes had a game-high 26 points and Dennis Smith Jr. had 25 for the Mavericks, who were playing on the road for the only time bridging two- and four-game homestands.
Dirk Nowitzki bombed in five 3-pointers to account for almost all his 18 points. The Mavericks connected on 13 of their 29 3-point attempts.
Dwight Powell grabbed a team-high 11 rebounds for Dallas.
Barnes and Smith had four points apiece in the Mavericks' 10-0, game-opening burst.
The Mavericks went on to lead by as many as 11 in the first quarter and by 14 in both the second and third periods before the Bulls rallied.
Chicago outscored Dallas 30-15 over the final 12 minutes.
--Field Level Media
Dallas | Chicago | |
Harrison Barnes 26 | Scoring | Bobby Portis 22 |
Wesley Matthews 4 | Assists | Kris Dunn 7 |
Dwight Powell 11 | Rebounds | Lauri Markkanen 12 |
Harrison Barnes 7 | Free Throws Made | Kris Dunn 3 |
Yogi Ferrell 2 | Steals | David Nwaba 3 |
Nerlens Noel 2 | Blocks | Kris Dunn 1 |
Team | Points | FG% | 3PM-3PA | FTM-FTA | Assists | Rebounds | Blocks | Steals | Turnovers |
Dallas | 100 | 41.7 | 13-29 | 17-21 | 21 | 46 | 4 | 6 | 17 |
Chicago | 108 | 47.2 | 10-27 | 14-20 | 24 | 45 | 2 | 10 | 13 |