The Vertical's Shams Charania reported on Sunday it is two-year contract worth $27 million
According to Charania, Mirotic also has the right to veto any trade in the first year of the deal.
Mirotic put up numbers in line with his career stats during the 2016-17 campaign, having averaged 10.6 points, 5.5 rebounds and 1.1 assists while shooting 41.3 percent from the field and 34.2 percent from three-point range across 70 appearances.
His player efficiency rating is cause for concern, though, as it dropped for the second straight year. The third-year pro posted a 17.9 PER as a rookie with the Bulls, but the figure dropped to 15.6 during his sophomore campaign and 14.5 this past season, according to Basketball Reference.
The low point came in March when he was briefly removed from the rotation. He admitted the situation took a mental toll, per Joe Cowley of the Chicago Sun-Times.
"This season has been hard," Mirotic said. "It's been very difficult for me to find a way to enjoy the game. There are a lot of reasons. One of the reasons is me, too. I understand that."
An ever-changing role is nothing new for the 26-year-old former Real Madrid star. He has frequently switched between Chicago's starting lineup and bench since making the jump to the NBA.
Nevertheless, Vincent Goodwill of CSN Chicago noted Mirotic continued to speak highly of his time with the organization as his future came into question during the latter stages of the season.
"I just wanna leave a good impression for the Bulls," he said. "Whatever decision they make. It's been a pleasure. A lot of people dream to be here; I was one of those guys when I was in Europe. I was really like, 'I wanna go there and play for the Bulls.' The history they have. For me, it's a dream come true."
Ultimately, the Bulls felt he remained an important enough piece of the rotation to keep him in the fold moving forward. It bears watching whether any other changes they make during the offseason will result in a more defined role for him next season.
Mirotic has enjoyed stretches where he looked primed to become a high-impact asset for Chicago, particularly as a rookie. Now the question will be whether he can turn that remaining untapped potential into on-court production as he heads toward what are typically a player's peak years.