Miller spent training camp with the New England Patriots but has not played since tearing an ACL in the 2019 preseason.
Bears offensive coordinator Bill Lazor held the same title in Miami when Miller lined up in the Dolphins' backfield in 2014 and '15.
Miller is expected to eventually be elevated to Chicago's active roster as the Bears attempt to replace all-purpose back Tarik Cohen, who suffered a season-ending torn ACL in Week 3's victory over the Atlanta Falcons.
The Bears rushed for only 28 net yards in the 19-11 loss to the Colts.
Chicago released former seventh-round pick Stephen Denmark, a defensive back, to add Miller to the practice squad.