The specific reason for the suspension was not disclosed in a statement issued Wednesday, roughly five hours before the Tar Heels' game against Georgia Tech.
Coach Roy Williams says McDonald "did not do what we expect of our student-athletes," and McDonald says he did not take care of his responsibilities as a student-athlete.
McDonald missed the past three games with an injured right knee. Williams says the junior guard would have been medically cleared to return this week.
The school says McDonald will return Feb. 2 when UNC plays Virginia Tech.
He missed all of last season with a right knee injury and is averaging 8.4 points this season while shooting 43 percent from 3-point range.