Mansell has been awarded the contract to build the Eton Manor Paralympic Games venue, the last major deal to be awarded by the Olympic Delivery Authority.
Eton Manor is on the former site of the Lea Valley Eastway Sports Centre to the north of the Olympic Park.
It will house three Olympic-size swimming pools, one synchronised swimming pool and one water polo pool to be used for athlete training during the Olympics.
During the Paralympic Games, Eton Manor will host Wheelchair Tennis with temporary seating for 10,500 spectators.
Following the Games the site will house a number of new facilities including a hockey centre with two competition pitches, permanent seating and space to accommodate temporary spectator seating for major events, along with a tennis centre with four indoor and six outdoor courts, and five-a-side football pitches.