The tailback, who will be a junior this season, suffered the injury while riding an ATV, according to multiple reports. Georgia, however, would not confirm the circumstances, saying only that he broke his arm in an accident.
The school said Michel is expected to make a full recovery, but it did not provide a timeline. Georgia opens its season Sept. 3 against North Carolina.
Michel, 5-foot-11 and 212 pounds, helped Georgia to a 9-3 record and a win in the TaxSlayer Bowl against Penn State last season after former Heisman Trophy candidate Nick Chubb was lost to a gruesome knee injury in the sixth game that required surgery.
Michel finished the season atop the team's stat charts, with 219 carries for 1,161 yards and 8 touchdowns.
His injury puts the Bulldogs' running game in a precarious position, as Chubb's status also remains up in the air.