The ex-Chelsea and England Under-21 international was surprisingly shown the door at the end of last season despite helping to keep The Lions up after taking over from Lenny Pidgeley between the sticks.
He has now signed a one-year-deal with Bradford City after manager Stuart McCall revealled to the Telegraph & Argus that he based his final decision on a glowing report from Jackett.
"I was a bit surprised he wasn't offered anything by Millwall after playing regularly last season," said McCall. "But I spoke to their manager and the goalkeeping coach and both recommended him to us."