Matthew Hermann, 20, had pleaded guilty in October to misdemeanor battery on Joshua Merritt in December 2011, the Chicago Tribune reported Thursday.
At the time of his plea, Hermann also agreed to participate in a "peacemaking circle" with the victim, his family, clergy and school counselors.
In handing down the sentence usually reserved for juvenile proceedings, Judge James Linn also sentenced Hermann to two years' probation.
Prosecutors said Hermann and two juvenile friends put a noose around the neck of the then-17-year-old Merritt and hurled racial epithets at him because of his friendship with one of the boy's female cousins. Merritt ran outside but was followed by one of the boys, who held a knife against his throat.
One of the boys pleaded guilty to battery and was sentenced to two years' probation. The third teenager is due in court next week.
After the hearing, Hermann said there had not been a racial motive in the attack, adding he still sees Merritt occasionally at the community college where they both attend class,