Januzaj has broken onto the first-team scene this season and become one of the few bright spots in David Moyes' troubled first few months at the club.
The 18-year-old has already been rewarded with a new five-year contract and made his Champions League debut in Tuesday's victory over Shakhtar Donetsk.
It is clear, despite United's present problems, Januzaj has a long-term plan that revolves around remaining at Old Trafford.
"My first opinion was to sign for Manchester United," Januzaj told MUTV.
"It was my first choice and I have signed for them.
"I am happy here. If I could play all my life at Manchester United I would do it for the club."
Moyes has largely been using Januzaj in wide positions.
However, the youngster, who was born in Belgium but is yet to commit his international future to any country given his Kosovan background, eventually feels he will move into a more advanced role.
"My best position will behind the striker as a number 10," he said.
"I always used to play there when I was really young. I can also play on the wings and I always do my best. I would do that even if it was at left-back. It is my job.
"But number 10 is the position I always wanted to play."
For now though he just wants to make the most of his opportunities.
Scoring twice on his first Premier League start at Sunderland in October was not a bad way to make his mark.
However, Januzaj understands there is much still to do - especially when he has set his goals so high.
"My parents always told me to stay on my feet and keep working for myself and, if I can, try to be the best player in the world," he said.
"Football is not about age. If you are good enough to play, you have to play.
"The boss gave me a chance and I couldn't have asked for more than to score two goals on my debut.
"I was really happy with those goals. Now I have to continue and score more if I can because I have to prove I can play at first-team level."