The goalkeeper, who joined Saints from League 1 side Gillingham three years ago, has agreed a new deal that will see him remain at St Mary’s until 2019.
Gazzaniga made two Barclays Premier League appearances for Saints last season following an injury to Fraser Forster, playing against Leicester City and Aston Villa towards the end of a successful campaign for Ronald Koeman’s side.
The stopper, who made his debut in a 4-1 Capital One Cup victory against Stevenage in August 2012, has made 21 appearances in all competitions since his arrival at St Mary’s.
With Forster in impressive form last season, the 23 year-old played a key role in helping Saints win the Under-21 Premier League Cup, playing in both legs of the final against Blackburn Rovers.
Executive Director of Football Les Reed said: “We are delighted that Paulo has committed his future to Saints.
“We now have an excellent pipeline of talented goalkeepers throughout the Academy and within our professional ranks, providing us with a level of competition and depth all the way down to under-16 level and beyond, which is healthy for our future.
“Paulo has had great experience in the Premier League and the Football League, and has proved to be an excellent option in backing up the senior goalkeepers and challenging for a first-team place.
“We hope Paulo will develop into a top ‘keeper and achieve international recognition. He is an excellent professional, a popular lad and deserves this opportunity.
“Kelvin Davis, Fraser Forster and Maarten Stekelenberg provide excellent role models for these youngsters and, with coaches Ryan Flood, Vince Bartram and England’s Dave Watson, they could not be in a better place for their development.
“Paulo Gazzaniga can lead the way to a bright and long future for the number-one spot at Saints for years to come.”
Gazzaniga added: “I’m very happy.
“Since I came here from Gillingham, I’ve been growing up every day and with every training session and game. I’ve worked with different coaches and I’ve taken positive things from all of them.
“I think I’ve grown, not only with the technical things but as a human. I’ve experienced how to be a teammate.
“Every new person who comes to the club says that Southampton is like a family, and I can still say the same after three years. I am very comfortable here.
“Of course, if you ask any player, getting minutes is important but I am realistic – I know the goalkeeper position is difficult. I will still keep growing and keep training.
“I am very excited about the future and very motivated also. We have a very good and strong team with a lot of players, and I think it’s going to be a very good season.
“We can still improve from last year, so I think and hope that this year is going to be special.”