The 22-year-old spent the 2024/25 season with the Highbury Stadium outfit, making 35 league appearances for the Cod Army.
A deal with the League Two outfit has been concluded in advance of Monday's upcoming transfer deadline.
Rhys, who spoke to MUTV before Christmas to help promote mental health and suicide awareness, after losing his father, came through the ranks with the Reds.
He was not only captain of the 2021/22 FA Youth Cup-winning side but also scored in the final against Nottingham Forest, at Old Trafford.
Joining the club at Under-10 level, Rhys has been a model professional throughout his time with club and a popular member of our Academy squads.