The move calls time on the Academy graduate’s 14-year association with the Club, who he joined aged eight.
The Manchester-born winger progressed through City’s youth set-up, winning the Academy Players’ Player of the Year award in 2013/14 and was rewarded with his first professional contract in July 2014.
Having impressed at U18 and EDS level, Barker toured Australia and Vietnam with the first-team in the summer of 2015, signing a five-year contract extension in August of that year.
Manuel Pellegrini included him in several matchday squads and handed him his first-team debut as a substitute in the FA Cup fifth round defeat to Chelsea in February 2016.
Three successive season-long loans followed, at NAC Breda, Hibernian and most recently at Championship outfit Preston North End, where he played 20 times in the 2018/19 campaign.
Everyone at Manchester City thanks Brandon for his efforts and wishes him the best of luck at Rangers.