Ronald Koeman has been appointed as the new manager of Saints, signing a three-year deal with the club.
The Dutch legend replaces Mauricio Pochettino, who walked out of St Mary's last month to join Tottenham Hotspur.
Koeman's brother, Erwin, has been appointed as his assistant manager, while Jan Kluitenberg has followed him from previous club Feyenoord as assistant first team/physical coach.
A "high-calibre" goalkeeping coach will be appointed in the near future.
Koeman said of his appointment: “I am thrilled to be the manager of Southampton Football Club.
“From my very first meeting with Les Reed, I could see clearly that this was the right club for me. We share the same philosophy of football, and the same belief in how to develop the club.
“Southampton have a talented first-team squad, a world-class academy and the infrastructure to sustain success in the Premier League.
“The opportunity to continue the development of this famous football club was simply too good to turn down. I cannot wait to get started.”
As revealed by the Daily Echo, Saints made a formal offer to Koeman on Friday, having identified him as the number-one candidate for the job.
Advisers and lawyers working on his behalf went through the contract over the weekend, with the 51-year-old arriving in Southampton today to sign it.
Koeman first held talks with the club two weeks ago, impressing chairman Ralph Krueger and executive director Les Reed.
Reed said: “We are extremely pleased to have secured a new manager of Ronald Koeman’s calibre and status within the game.
“In appointing Ronald we have concluded our search for a manager who shares our values and vision for the future of Southampton Football Club.
“As part of our ongoing scouting process, we have been following the development of Ronald’s coaching career for some time and, through a more formal process this month, immediately identified him as our number-one choice.
“From the moment we met with Ronald, it was clear he had the vision and ambition to take our club forward, that he shared our football philosophy and could see the opportunity to move our club to the next level.
“The club, the players and the fans will all be excited to have a man of Ronald’s experience at the very highest level joining our club.
“Ronald’s passion for the opportunity here at St Mary’s was very clear, and we look forward to continuing our growth with him as part of our team.”