Delgardo has been plagued by injuries since arriving at St Mary's in 2001 and manged just one start and five substitutes appearances last season.
"Tino was very popular at Southampton and in a way he became a bit of a cult figure," chairman Rupert Lowe told Saints official website. "We are all sad to see him go and wish him well for the future. He is a quality player but unfortunately we could not get him fit enough for the Premiership despite a lot of effort by a lot of people. "I have never worked as hard with anyone as I have done with him and he dined in the last chance saloon more than once."