The 30-year-old, who moved to City in June 2003 from Dundee United, has signed a two-year deal at Rugby Park to take up the number one spot after Jim Jefferies released both Colin Meldrum and Francois Durbourdeau.
His departure leaves Bantams boss Colin Todd with no keeper as he somehow tries to prepare his depleted squad for their first pre-season match on Friday against Harrogate Town.
Meanwhile on the transfer front, City have seen another two players slip through their fingers.
Danny Cadamarteri has joined Leeds United and Australian under-23 international Gareth Edds has been snapped up by Milton Keynes Dons.