The 19-year-old, who can operate at centre-back or as a holding midfielder, was on trial with the Hammers towards the end of last season.
Ekwah played two matches for the academy’s under-23 team and it is understood he managed to impress West Ham coaches.
The club are now set to sign Ekwah and bring him to the club on a permanent basis this summer.
The signing of Ekwah will be viewed as a coup for West Ham as he was highly rated when coming through the ranks at Nantes.
The Frenchman then moved to Chelsea and he has been playing for their youth sides over the past few years.
Ekwah has now been tempted across London, though, and is set to sign for the Hammers during the upcoming transfer window.