Adams, 23, has signed until the end of 2014 after finishing fourth in the club's best and fairest.
Used mainly at half-forward but with stints through the midfield in 2011, he averaged 20 possessions a game and kicked 16 goals for the year.
"It is another show of faith by one of our future leaders with Leigh agreeing to a new contract," North chief of football Donald McDonald told kangaroos.com.au.
Adams' impressive season comes off the back of a third-placed finish in the 2010 Syd Barker Medal.
"He is fast becoming one of our most consistent players. It is a credit to Leigh that he has overcome many injury setbacks to become the player he is today."
Selected in the rookie draft in 2006, Adams has played 44 games since his debut.
