The running back from Iowa State was the first player taken by the Bears after they traded up with New England to grab him at No. 73 overall. Chicago had previously traded away its first and second-rounders.
Montgomery ran for 2,925 yards and 26 touchdowns in three seasons at Iowa State. He had 1,216 yards rushing and 13 TDs as a junior.
With the move announced Friday, the Bears have four of their five draft picks under contract. Cornerback Duke Shelley (sixth round) has not signed.