Portis will serve the suspension beginning with the Bulls' season opener at Toronto on Thursday night.
The suspension came after Portis and Mirotic got into it during a practice on Tuesday and ended with Portis laying out Mirotic with a single punch that broke multiple bones in Mirotic's face and gave him a concussion.
Hertha Berlin Players 'Take A Knee' Before Defeat Against Schalke
The German league, the Bundesliga, backed the players by calling it " a great and important gesture ". Players of Hertha Berlin kneel before a match in Berlin on October 14, 2017 .
As told by ESPN's Adrian Wojnarowski, the two players had been talking trash during a practice scrimmage and got into a shoving match that escalated when Mirotic charged at Portis twice. Mirotic dropped to the floor and lay there for several minutes before getting up. In fact, the fight sent forward Nikola Mirotic to the hospital.
Portis, also a forward, averaged 6.8 points last season for Chicago.
Portis will be eligible to return for the Bulls' ninth game of the season against the Raptors on November 7.
Mirotic, 26, averaged 10.6 points and 5.5 rebounds in 70 games last season and was expected to have a starting role for the Bulls this season after inking a two-year deal worth $12.5 million with Chicago. Mirotic has to wait until concussion symptoms subside before doctors can perform any surgery, so the four-to-six-week timetable could change.