The deal extends his stay at his only NRL club to 11 seasons.
Ropati, who was about to come off contract, was happy to sign for a further season.
“It’s a fair way for both parties and I’m confident my form this year and next will warrant a further extension,” he said.
Warriors’ coach Brian McClennan said Ropati’s experience and versatility were important to the club.
“With so many young players coming through into our NRL side, we need good people like Jerome to mentor them and help us with our culture,” he said.
Ropati has played 137 first-grade games and 11 Tests for New Zealand.