The 26-year-old has spent the last three months at Blundell Park, scoring eight goals in 13 matches for the Mariners.
And Hannah netted the winner in his final loan game, a 1-0 victory over Wrexham on Friday, a result which sent Grimsby top of the Blue Square Bet Premier.
The forward is now back with Bradford and hoping for a place in Phil Parkinson's squad for the Boxing Day home game with Accrington Stanley.
"He did really well during his time at Grimsby and we were all pleased to see him get some goals under his belt," boss Parkinson told the club's official website.
"There were times when we could have called Ross back given the amount of games we've had in periods this season, but we decided to be fair to Ross and to Grimsby. We wanted to give him the full three months.
"As you may expect given the amount of goals he's scored, there has been some interest in Ross from other clubs.
"If any of the interested clubs make an offer for Ross that we feel is right for the club and for Ross, we'll listen to it. Until then though, we look forward to welcoming him back and working once again with him."
Meanwhile, first-year professional Adam Baker has joined Blue Square Bet North side Harrogate Town on a month's loan.