The 25-year-old will not remain at the Hunter Stadium until the end of the 2017 campaign.
Since arriving at the club in 2008 Uate has developed into a formidable player and courted the interest of rival clubs as well as Japanese and European rugby league clubs.
Uate said: “I love playing for the Knights and am really happy to stay here for the next four years. I can’t imagine playing anywhere else and the decision to re-sign was an easy one. Now my future is secured I am even more excited about running on to Hunter Stadium on Monday night.”
Knights CEO Matt Gidley said the re-signing was a huge boost ahead of the season opener with the West Tigers: “There was obviously some interest in Aku from other clubs, so it is pleasing we have been able to secure him at the Knights for the next four years.
“As a fan favourite, we know our members and supporters will be happy to hear this news today. Aku is one of the most exciting players in the competition and we look forward to his further development at the Knights.”