The 26-year-old has agreed a four-year deal at St. Mary’s and joins for an undisclosed fee from Scottish champions Celtic.
Forster travelled with Roy Hodgson’s squad to the World Cup, where he worked with Southampton’s new goalkeeping coach, Dave Watson.
"At 26, he will enjoy the best years of his career at Southampton"
New boss Koeman on Forster
The ‘keeper began his career with Newcastle United, and had loan spells at Stockport County, Bristol Rovers and Norwich City before joining Celtic in 2010.
He went on to win three league titles and two Scottish cups as well as gaining experience in the Champions League during his time in Glasgow.
Saints boss Ronald Koeman told SaintsFC.co.uk: “Fraser is a very talented player and we are delighted to be able to bring him to Southampton. This is another important part of our rebuilding process ahead of the start of the season.
“The fact that he has worked with Dave Watson before means we already know all about his strengths and weaknesses, and I am confident that we will be able to help him improve even further.”
He added: “Fraser is the perfect fit to help complement the players we already have, and he will add a lot of quality to the squad.
“He is an exciting English player with a very good reputation within the game and, at 26, he will enjoy the best years of his career at Southampton.”
