Sidelined since last season's 1872 Cup victory over Edinburgh at Scotstoun due to a knee injury, the 29-year-old has been working closely with the club's medical team as he continues to work his way back to full fitness.
Scorer of eight tries in 28 appearances for the club to date, the Hihifo Rugby product's explosive brand of ball-carrying has seen him become one of the BKT United Rugby Championship's most destructive presences with ball in hand.
Vailanu also represented his country at the 2023 Rugby World Cup, featuring in all four of Ikale Tahi's fixtures at the tournament, including a 25-minute cameo off the bench against Scotland in Nice.
"I'm loving my time in Glasgow," Vailanu told glasgowwarriors.org.
"Ever since the first day I arrived here, everyone made me feel so welcome. The environment here really allows me to push myself and challenge myself to get even better, because you know that everyone at this club - from the boys on the field to the team behind the scenes - is striving to be the best.
"I'm very grateful to the coaches for the trust that they've placed in me so far and for the opportunities they've given me. It really motivates you to go out and perform at your best, and help this club reach the heights we're all aiming for.
"I love this club and I want to get back on the pitch as soon as possible. The boys were outstanding in the back end of last season, and I want to get myself physically and mentally ready to get out and help to do my bit for the team.
"I love the Warrior Nation too, and I can't wait to get out there again. It's been frustrating not being able to be out there in front of them, but sometimes it is what it is - you've just got to get yourself right and then get back out there. The physios and medical team have been great, and I can't wait to get out there once they give me the green light."
Head Coach Franco Smith added: "We're pleased to retain Sione's services for another couple of seasons, as we continue to build towards what is set to be another physically demanding campaign.
"He is someone that has bought into our culture and our environment, and his performances on the field have reflected that when he has been selected.
"Our medical and strength and conditioning teams have been working closely with him as he continues his return to match fitness, and we look forward to seeing him on the field again in the near future."