Johnson, 20, tore his ACL while scoring a touchdown in Michigan's season finale against Ohio State on Nov. 29. He also tore his ACL in Michigan's 2013 season opener and missed the remainder of the season.
In six games this season, Johnson had 60 carries for 361 yards and four touchdowns. He set a career-high with 122 yards and two touchdowns on 16 carries against Indiana on Nov. 1. He also scored two touchdowns against Ohio State.
Michigan fired head coach Brady Hoke after the team finished 5-7, failing to qualify for a bowl game for just the third time since 1974. The school has reportedly offered San Francisco 49ers head coach Jim Harbaugh a six-year, $48 million contract to replace Hoke.
Michigan will begin the 2015 season on September 3, when the Wolverines travel to face the Utah Utes in a true road game.
- Brad Rowland