In a corresponding move, the Colts waived linebacker William Ossai with a non-football illness designation.
The 6-foot, 220-pound Green appeared in five games with the Detroit Lions as a rookie in 2017, rushing for 165 yards and two touchdowns on 42 carries. He also had two receptions for 14 yards.
Green rushed for 2,072 yards and 19 touchdowns in 46 games at the University of Cincinnati.
Ossai signed with Indianapolis on May 1. He started 22 of 48 games at San Jose State, registering 169 tackles, including 17 for losses, and 2.0 sacks.