The Republic of Ireland international arrived in November when he signed a short-term contract and agreed a further five-month stay in January. He made 24 appearances for Mick McCarthy's side last season.
McCarthy told the club's official website: "We have resigned Hunty and we're delighted about that.
"He's a great character and is good to have around the place, not just for what he brings on the pitch but off it as well.
"The players took to him straightaway when he first arrived here last season.
"He's an experienced player who has played at the highest level and he will be a great asset to the squad."
Ipswich has already signed Alex Henshall and Cameron Stewart during the close season.