The two men are old team-mates from their time at Preston, winning the Division One title together in 2000.
The 35-year-old midfielder said: "It's a pleasure to be here, it's great to come to a club that has got so much ambition.
"I've spoken to the manager and he's expressed where he wants the club to go and he's been backed by the chairman and so it's an exciting time.
"It's good he (Graham) thinks I can come in and improve the team.
"Obviously, I've not played for a couple of months while at Hull, so this is a great opportunity to put myself in the shop window and until then do the best I can for Fleetwood Town football club."