Kolo’ofai signed for the Falcons in summer 2014 from French side US Colomiers but as a result of injury made only three appearances for the North East side.
After making his club debut against Northampton Saints in the LV= Cup, Kolo’ofai picked up a try for the Falcons in his next appearance against Sale Sharks later in that competition.
The New Zealand-born Back Row then made his Aviva Premiership debut on the final day of the 2014/15 season in the Falcons’ victory over Harlequins.
Speaking of the news, Director of Rugby Dean Richards said: “Uili has had a frustrating season with regards to injuries and we share his disappointment about the amount of game time he has missed as a result.
“As a club we need to encourage consistency within the squad and although Uili has made a significant contribution when he has appeared for the club both parties agreed that it is necessary to part ways to ensure that consistency.
“Uili leaves with our very best wishes for the Rugby World Cup and beyond, and our thanks for his contribution to the club both on and off the field during his year in the North East.”
Kolo’ofai will represent Tonga in the upcoming Rugby World Cup after a late call up to the national squad.