“The Scarlets supporters and community have made me and my family feel really at home,” said Fifita.
“This means a lot to me and is something I don’t take for granted.
“By extending my contract I am demonstrating the confidence and commitment I have in this club, the staff and the direction we are heading.”
After making 11 appearances for New Zealand, Fifita switched to the country of his birth, Tonga, before the 2023 World Cup in France.
“It is fantastic Vaea has committed,” said Scarlets head coach Dwayne Peel.
“He is a world-class athlete who has become a favourite with supporters since he arrived at the club.
“He is a special player who can produce special moments.
“You only have to look at the tries he has scored for us and he is also one of the best line-out forwards in the United Rugby Championship.”