The 24-year-old Tongan international joined the Panthers ahead of the 2017 season.
Langi had suffered a season-ending ACL injury in 2016 and his career was at somewhat of a crossroads.
However he was diligent and committed in his rehabilitation and after regaining full fitness, he scored three tries in 13 appearances for the Panthers in the Intrust Super Premiership NSW.
“Panthers gave Samisoni the chance to resurrect his career last off-season,” Panthers Executive General Manager Phil Gould AM said.
“He worked extremely hard and went on to play some great football for the Panthers in the ISP competition.
“We wish Samisoni all the best for the future.”