In a statement released through Southampton's Twitter account, Pochettino said: "I would like to thank everyone at Southampton for the support that myself of my coaching team received during our 18 months at the club.
"We have been on an incredible journey and enjoyed some great experiences. I will always have fond memories of my time at St Mary's and wish everybody the very best for the future. I hope the team can continue to prosper."
Spurs needed a new manager after firingTim Sherwood at the end of the 2013-14 Premier League season.