The 18-year-old has broken into the Red Devils first team this season, making 13 appearances and scoring twice in all competitions since debuting in the Community Shield in August.
Despite reported interest from United's fierce rivals Manchester City, Januzaj has recently signed a five-year contract extension at Old Trafford, and the winger has his sights set on many more.
"My first opinion was to sign for Manchester United - that was my first choice," he told MUTV. "Now I've signed for them and I'm happy here. If I could play all my life at Manchester United, I would do it."