Yoshida has been an important part of the club's progress since he arrived at St Mary's in 2012 and the new deal is a reward for his contribution.
Last season, the 28-year-old became the first Japanese player to play 100 Premier League games.
"We are extremely pleased to have reached a new agreement with Maya, who is a vital part of our squad, not only on the pitch, but off it," Southampton vice chairman Les Reed said.
"Maya is a player who has taken great strides in his game during his time with us, and his influence was felt particularly last season.
"He formed outstanding partnerships with both Virgil van Dijk and Jack Stephens, helping the team reach the League Cup final.
"Maya is an excellent example for any young professional to follow and it was important to ensure that we extended our commitment with him."
Since joining from Dutch club VVV-Venlo, Yoshida has grown to relish life in England and he had no qualms about extending his stay.
"There was no reason to leave the club. I have been here for five years. In that time, I have had difficult moments, good moments – everything," he said.
"I feel like it's my home and I'm very happy to continue my journey with Southampton. It's a new chapter for my career."