The 15-year-old spent time training with United's youth set-up in November and again in January.
On the back of the trials Sir Alex Ferguson has sanctioned the deal to bring in Ekangamene, who has signed a pre-contract with the club.
He will become a professional at United when he turns 16 but until then he will stay with Antwerp.
"He is a great talent," Antwerp youth director Alex Vervecken told HNB.
Antwerp have confirmed the deal on their website, commenting that they are happy to have agreed terms with United.