Flanagan joined the club on Wednesday and has linked up with the rest of the squad on the pre-season trip to Lanzarote.
Flanagan is an England Academy international and figured recently in the matches against the Australian Schoolboys.
Mark is also a useful goalkicker and signed for the Bulls from amateur club Saddleworth Rangers as a 16 year old. His father Terry played for Oldham and won four Great Britain caps between 1983 and 1984.
Speaking about the addition, Head Coach Brian Noble said,
"Mark is a player I know well from his academy performances at Bradford. We are delighted he has agreed a two year deal with us. He is only a young man and will be looking to work his way through from our Under 21 squad."