The 63-year-old is one of the sport's most respected coaches and he has left his role as director of rugby at Wakefield to take over at Odsal.
Kear has signed a three-year deal in order to give him the time he will need to revive the Bulls.
Their decline from Super League's dominant force to now a League One side has been a dramatic one, with financial and ownership problems besieging them.
The decision to employ Australian Geoff Toovey for the 2017 season backfired as he was unable to get a visa for most of the year and now the Bulls board have opted for a tried and tested approach.
"It is going to be a new experience, it is an iconic club and it has been one of the greatest names in the Super League era, especially in the early part of it," said Kear, who is best known for winning the Challenge Cup with Sheffeld (1998) and Hull (2005).
"Obviously, it has come upon hard time performance wise, so I'm really excited to first of all be enlisted with the job of bringing stability to the place but then also gradual improvement.
"We want to regain our place where we feel the infrastructure of the club belongs, which is obviously in the highest level."
Fresh from coaching Wales at the recent World Cup, Kear will start work immediately with compensation having been agreed with Wakefield.
"We're ecstatic that John has committed his time to us. He's a remarkable coach and a great man that has a lot to offer the club," co-owner Andrew Chalmers told Bradford's official website.
"Moving forward John will bring an experienced and professional approach and really benefit the club as he will implement a winning culture into the team.
"He's a man with a lot of knowledge of the game who will offer a huge lift to the squad, especially the younger generation."
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