With Arsenal's third place finish ensuring Champions League football for Arsene Wenger's side, their Europa League spot for winning the FA Cup goes to the next highest placed Premier League side, which is seventh-placed Saints.
Ronald Koeman's outfit will enter the competition at the third qualifying round, with the first leg on July 30.
"I think to sum it up in one word is proud
The feeling of finishing seventh and being in a European competition - the only word I can use is proud," club captain Kelvin Davis told Southampton's official website.
"I'm proud of my team-mates, proud of the club and proud of what everyone has achieved.
"To be a club like Southampton and progress as we have done, to me it's the natural next step to qualify for European competition.
"I think we've progressed year on year and for us to finish seventh in the Premier League ahead of so many fantastic football clubs to put ourselves in this position warranted the opportunity to play in Europe.
"We needed Arsenal to win the cup but at the same time that position of seventh is what has given us the opportunity.
"We're very excited and looking forward to the prospect of playing in the Europa League next year
But we've still got a hurdle to come across (the third qualifying round) and that's what we'll be focusing on."
Southampton last entered Europe 12 years ago after they lost to the Gunners in the final of the FA Cup and t his is the first season that the European place has gone to the next-best Premier League side rather than the losing finalists
The Saints will join Liverpool, Tottenham and West Ham in next season's competition.
Source : PA