The 32-year-old was handed a six-month ban last August for breaching betting rules and retired two weeks later.
He was appointed player welfare manager at Super League side Warrington in October and he will retain his role with the Wolves.
"It's an exciting time and I'm really looking forward to it," Mathers told BBC Radio Leeds.
"I stick by what I said when I retired and I stand by my reasons for doing that.
"I think the old romantic in me wants to be a part of getting the Bulls back in the Super League."
Bradford Bulls have signed full-back Richie Mathers, four months after he announced his retirement from the game.