With his career predominantly spent in the lower leagues, Lambert 31, joined Southampton in 2009 and has scored more than 100 goals for the south-coast club.
He helped secure successive promotions to the top flight after they were relegated to the third tier of English football at the end of the 2008/09 season.
"Rickie Lambert is a very special player for Southampton Football club," team manager Mauricio Pochettino told the club's website.
"To have scored over 100 goals is a remarkable achievement, and one which he has made possible thanks to hard work and dedication."
Back in the Premier League this season after a seven-year absence, Southampton sit 16th on 31 points, four points above the relegation zone with eight matches remaining.
"In my time at the club I have been impressed by his mentality and commitment to improving himself in training - attributes that have allowed him to adapt to the Premier League so well," added Pochettino.
"I am delighted that Rickie has committed himself to the club... and have no doubts that he will continue to deliver for Southampton as we look to push on to the next level."
Liverpool's Uruguay forward Luis Suarez tops the Premier League scoring charts with 22, followed by Dutchman Robin van Persie of Manchester United on 19, Tottenham Hotspur's Welshman Gareth Bale with 16 and Chelsea's Senegalese front-man Demba Ba on 15 along with Spaniard Michu of Swansea City.
