The former Stoke defender wasn't assured regular first team football at the KC Stadium so opted to cross the Humber and join Russell Slade's Town revolution.
However there already appears some confusion over Whittle's contract. The official site is reporting a one-year contract, whilst the Grimsby Telegraph reports a three-year deal.
Speaking to the official site, Whittle spoke of his delight at signing for Town and his desire to help lift them back up the divisions.
"I got a phone call asking me if I was interested. I was offered a contract at Hull but I wasn't first choice and I thought that I would have more chance of playing if I moved to Grimsby," he said.