Juventus confirmed in a statement on their official website the deal was worth an initial 17 million euros (15.39 million pounds), which could increase by a further three million euros.
The 23-year-old Lemina won the Serie A title and the Italian Cup twice with the Turin club and featured in last season’s Champions League final defeat by Real Madrid.
"I think that it was the project that attracted me the most and the one my family was really behind. I am really happy to be here," Lemina told the club website.
Saints' previous record signing was Morocco midfielder Sofiane Boufal, who joined the south-coast club from French side Lille in August 2016.
Lemina's arrival is a boost for Southampton supporters after Netherlands centre back Virgil van Dijk said on Monday he had handed in a transfer request and expressed disappointment at the south-coast club's refusal to listen to offers for him.
Lemina is the club's second signing in the transfer window after Polish centre half Jan Bednarek from Lech Poznan.
"Mario is an outstanding talent who has already achieved a great deal in his career, winning a number of titles and gaining experience of playing on some of the biggest stages in world football," said Southampton Vice Chairman (Football) Les Reed.
"Investing in a player of Mario’s quality and buying from a club like Juventus is a significant statement of intent from the club, and this is a purchase that has set another club-record fee.
"Mario will complement what is already an extremely strong group of midfield players in our squad, and we are excited about what he will bring to the group.”
(Writing by Ken Ferris; Editing by Toby Davis)
Share
