The 18-year old winger told Kosovan broadcaster KTV that he sees his future at Old Trafford, contrary to rumours linking him with a move to Barcelona or even noisy neighbours Manchester City.
“I am happy at Manchester United and I want to commit myself 100 per cent in every game to do my best,” Januzaj said.
“I want to help Manchester United win the Premier League and become the best player in the world.”
His current contract runs out in June next year, but the new deal will tie his services to Manchester through till 2017.
The Belgian-born Kosovan has dominated headlines ever since he scored a brace and won the game for the champions against Sunderland on his full debut in the United starting XI. With a combination of flair and elegance, Januzaj has become a new favourite of the Stretford End.
His international future, though, remains uncertain.
Reports have emerged suggesting that Januzaj might be inclined to play for England, but only if the FA can change the rules, so that he can pull the Three Lions jersey on before 2018, as the current regulations dictate.
Also, more doubts were cast over his allegiance to Belgium after his father, Abedin Januzaj, had a falling out with Belgian national coach Marc Wilmots earlier in the week.
Wilmots told Belgian broadcaster RTBF that he believes there is no question whether Januzaj should play for Belgium, but that he will “make no promises, to Januzaj or any person.” Mr. Januzaj answered by calling the coach’s dealing of the situation ‘shameless’, and implied that the remarks can only further complicate an already intricate issue.