The Hawkeyes also announced the departure of running backs coach Lester Erb on Thursday.
No specific reason was given for Erb's departure.
Kennedy spent the past two seasons with the Buffaloes after working with current Iowa offensive coordinator Greg Davis for seven years at Texas. He replaces Erik Campbell, who left the program after last season.
Reid was the associate head coach and defensive coordinator at Virginia from 2010-12. Reid also spent 17 years as a head coach at VMI, UMass and Richmond.
Erb spent 13 seasons with coach Kirk Ferentz at Iowa, the last five working with the running backs.