Belgium coach Marc Wilmots has announced on his official Twitter account that Adnan Januzaj has committed his international future to the country.
Januzaj, 19, is also eligible for Kosovo and Albania. He was linked with England although he would have had to wait until he qualified through residence.
Any possible eligibility for Croatia, Serbia or Turkey had been ruled out by his father earlier this year.
The Manchester United winger has, somewhat surprisingly, not represented any nation at youth level but he has now opted for the country of his birth. The player was born in Brussels to Kosovan and Albanian parents.
He could be selected in Belgium’s 23-man squad for the World Cup finals even though he did not make himself available for any of their qualifiers.
With Kevin Mirallas an injury doubt for the finals the sudden availability of Januzaj could be a timely boost.
He burst onto the scene at the start of this season under now-sacked boss David Moyes at United, and his performances were rewarded with a lucrative new five-year contract in October.
Januzaj has scored four goals and provided four assists in 33 appearances — 17 from the start — in all competitions since making his debut in the Community Shield win over Wigan Athletic in August.
Belgium will face Algeria, Russia and South Korea in Group H at the World Cup finals.