Picamoles quits Toulouse for Saints
"I have taken my decision and told my current club. Next year I will leave for Northampton and for three seasons," the 29-year-old No.8 told RMC Sport.
"Above all it's a life decision. I have this opportunity that has presented itself and I will soon be 30, so to play in a foreign country has always appealed to me and now the chance is there to take it." he added.
"It is the right time to take on this experience," said the winner of two Top 14 titles and a European Cup.
The No.8 told Northampton's website why he'd chosen the English club.
"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."
Picamoles was one of the few bright sparks in the French World Cup campaign that ended with a heavy quarterfinal defeat at the hands of eventual champions New Zealand.
Director of rugby at the English club Jim Mallinder described the signing as "a real coup".
"Louis is a world class player and a proven performer at the highest level of club and international rugby," he said.
"He was France's standout 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."
Picamoles joined Toulouse from Montpellier in 2009 and has won 51 caps for France.
Agence France-Presse