Jim Mallinder believes the signing of Louis Picamoles is a ‘real coup’ for Saints.
Picamoles will move to Franklin’s Gardens on a three-year deal when his current contract at Toulouse runs out in June.
The 29-year-old has made 51 Test appearances for France and recently helped his country reach the quarter-finals of the World Cup.
He won the 2010 European Cup with Toulouse as well as back-to-back Top 14 titles in 2011 and 2012.
And Mallinder said: “Louis is a world class player and a proven performer at the highest level of club and international rugby.
“He was France’s stand-out performer at the World Cup and we’re excited by the prospect of him linking up with the quality players we have here already.
“He is still young and we believe that his best years are still to come. When we met it was clear that he has the drive and ambition to improve and be successful, and we’re delighted that he will be doing that here with us at Franklin’s Gardens.
“Louis is a fantastic addition to the squad and his signing is a real coup for the club as we look to continually improve and compete at the highest level, both in the Aviva Premiership and in Europe.”
Picamoles is relishing the challenge of representing Saints.
And he said: “It is going to be an honour to become part of a club as prestigious as the Saints.
“I’m really looking forward to learn more about the club, my future team mates, to play in the Aviva Premiership and to immerse myself in the English culture, especially my first big derby against Leicester!
“I’m really ambitious to win titles and I’m convinced that I will do this with the Saints.
“The club has all the coaches, players and staff to reach the top of the sport in England and in Europe, and I’m looking forward to arriving at Franklin’s Gardens.”