The 29-year-old centre arrived at Scotstoun in February on a short-term contract until the end of the season and was part of the Glasgow squad which won the Melrose 7s in April.
He made one appearance in the RaboDirect PRO12, when he came on as a substitute in the defeat to the Dragons at Rodney Parade.
Glasgow Warriors head coach Gregor Townsend said: "Folau (Niua) has had limited game time since joining us earlier in the year, with Peter Horne returning from injury and Finn Russell breaking into the team, but he has shown that he is a quality rugby player with a number of strengths.
"We'd like to thank him for his contribution this season and we wish him all the best for the future."
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland
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