Games against the Detroit Pistons on Tuesday and the Toronto Raptors on Thursday are off, the NBA said.
The NBA postponed 31 games because of Covid-19 last season.
The NHL - North America's elite ice hockey league - has also called off the next three games of the Calgary Flames because of a Covid-19 outbreak.
Six players and one staff member have entered Covid-19 protocols and the NHL said there was a "likelihood of additional positive cases in the coming days."
It is the third time this season an NHL team has been forced to pause its season because of an outbreak.
The NBA said 10 Bulls players and "additional staff members" had entered the league's Covid-19 protocols, meaning the franchise were at risk of not being able to field a team.
The Bulls players confirmed to have contracted the virus are DeMar DeRozan, Zach LaVine, Coby White, Troy Brown Jr., Matt Thomas, Javonte Green, Ayo Dosunmu, Alize Johnson and Derrick Jones Jr.
Photo Getty Images Caption: DeMar DeRozan is one of the confirmed Covid-19 cases in the Chicago Bulls squad