The 30-year-old former Blackpool shot-stopper (pictured) comes in following Walsh's knee injury which left Aidan Davison as the only senior keeper at the club.
Banks goes straight into the squad to face Rotherham on Saturday.
Bradford are suffering from a number of problems on the injury front, along with Walsh - who is yet to find out the extent of his leg injury, they also have trouble with defender Peter Atherton.
Atherton has been ruled out of action for a month with a groin injury, which is better news than midfielder Thomas Kearney received - after the younsgter learnt that his knee injury was medial ligament damage, which ends his season.
"I feel really sorry for Tom. It's a massive blow for him and for us because he has become such an important player for the team," said manager Nicky Law.
"It's just the story for us at the moment. We are taking two steps forward and five back.
"At least Peter Atherton's injury is not as bad as we feared. But he is still going to be out for four weeks which is a big loss.
"Peter's the sort of player that you only really notice when he is not there. He is an unassuming player who doesn't try and do anything clever but just gets on with the job.
"He is vastly experienced and reads the game superbly. He may not be the quickest defender around but he has a real calming influence out there. It's easy to forget about him because he just goes about his business but we shall really miss his presence."
