It has been reported by the British tabloid that the Hammers have paid £4 million to the Belgian club for the services of the 25-year-old, who can play as a defender, defensive midfielder and central midfielder.
The London outfit reportedly wanted to sign the Senegal international in the January transfer window, and have had to beat off competition from Premier League rivals Everton and Leicester City for his signature.
This means that Mbodj will become West Ham’s second signing of the summer following the acquisition of goalkeeper Darren Randolph on a free transfer after his departure from Championship outfit Birmingham City.
West Ham finished 12th in the recently concluded 2014-15 Premier League campaign with 47 points from 38 matches.
The Hammers are currently searching for a new manager following the departure of Sam Allardyce, whose contract was not renewed.