Wright finished last season on loan at St Mary' s Stadium while he was at West Ham and played a leading role in the club's survival bid, making seven appearances.
Wright told the club's official website: "I really enjoyed it at Southampton.
"It was a tough spell because the club was fighting relegation from the Championship. The games were tense, but the club survived which was fantastic.
"They are in a fight again to stay up this season, but I hope they can do it without taking any points from us."