Saints are delighted to announce the signing of Crystal Palace and England Under 21 defender Nathaniel Clyne.
The 21-year-old this morning signed a four-year deal to commit himself to the Club until 2016, and has flown out to join the squad on their training camp in Évian-les-Bains.
Clyne was out of contract at Selhurst Park but, due to his age, Saints are required to pay a fee to his former club.
Discussions between the two clubs regarding compensation are still ongoing. If a fee cannot be agreed, it will be set at an independent tribunal.
Right-back Nathaniel has been linked with the likes of Manchester United during the past 12 months, but he has chosen to make the move to St Mary's following talks with First Team Manager Nigel Adkins and Executive Chairman Nicola Cortese.
"I'm overwhelmed, really," Clyne told saintsfc.co.uk on his first full day in Évian.
"As soon as I heard that Southampton were in for me, I was happy and I knew that this was the place where I could try to improve my football, further my career and get a chance to play in the Barclays Premier League.
"It's a club with a lot of ambition - the gaffer told me that they would want to be pushing for European football.
"We've got good players here - a young bunch of good, talented players who are destined for the top, so I don't see why we can't do it.
First Team Manager Adkins was pleased by the acquisition of Clyne, saying: "We're delighted that we can finally announce that we've brought Nathaniel Clyne into the group to help us kick onto the next level.
"There's a lot of work going on behind the scenes all summer and, with [Head of Recruitment] Paul Mitchell and Nicola Cortese, we work very hard behind the scenes to make things happen.
"For the last three years Nathaniel has been a very attack-minded full-back who bombs on - he's got pace and he's a good one-on-one defender.
"He got into the Championship Team of the Year last year, and for such a young age he has had a lot of first-team football in the Championship.
"All being well, we can push him onto the next level now."
In Profile: Nathaniel Clyne
Clyne made his Crystal Palace debut as a 17-year-old in October 2008, starting a 3-0 win over Barnsley in place of regular right-back - and new Saints teammate - Danny Butterfield.
He went on to make 29 appearances during his debut season with the Eagles, signing a three-year contract in the process.
The Londoner was used more sparingly in his first full season as a first-team player, though he did still manage to play 28 times as well as scoring his maiden professional goal in a 4-2 win at Reading in December 2009.
His promising performances drew interest from the Premier League, with Wolverhampton Wanderers looking to take advantage of Palace's financial struggles by offering Clyne a move to Molineux in January 2010.
However, he decided to stick with the Eagles and went on to secure the Football League's Young Player of the Year award at the end of the 2009-10 season as well as helping to maintain Palace's Championship status.
Clyne played in every single one of Palace's 46 league games in 2010-11 - the youngster player to do so for a Football League club that season - as his reputation continued to grow.
International recognition soon followed: he had already played 19 times for England's Under 19 side by the time he received his first call up to Stuart Pearce's Under 21 squad in November 2011.
Clyne started in the Young Lions' 5-0 UEFA Under-21 Championship qualifying win over Iceland, following up his debut with another cap in a narrow loss at the hands of Belgium a few days later.
The full-back remained an important part of the Palace side during his final season at Selhurst Park, though he did not make his first appearance of the campaign until mid-October due to an injury picked up in a summer friendly against AFC Bournemouth.
Nathaniel was linked with a move to Old Trafford in January, but chose to wait until the summer to make a decision about where his future might lay.
He was named in the 2012 Championship Team of the Year alongside Jay Rodriguez, Rickie Lambert, Adam Lallana and Kelvin Davis before deciding to join up with Saints for the 2012-13 Barclays Premier League season.