Harford who scored one goal in twelve minutes of football for the Sky Blues back in 1993, has been assistant at Luton Town,Swindon and caretaker manager of Nottingham Forest.
He replaces Alan Knill who saw his side relegated after a 4-3 defeat at Ipswich on Tuesday and will be the third manager of the season for Rotherham with Ronnie Moore also losing his job at Millmoor.