The three-year upgrade, due to start early next year, is the first major contract awarded under Thames Water’s AMP7 schedule.
Laing O’Rourke will build a completely new inlet works and extend aeration lanes and settlement tanks.
Beckton will also be prepared to receive wastewater from the 25km Thames Tideway Tunnel under the River Thames that is due to be completed by 2024.
John Bentley, Thames Water’s capital delivery director, said: “Awarding this contract is a significant milestone as it is the first major project awarded as part of our £5 billion capital investment plan for the next five years.
“By ensuring we can take the flow from the ‘super sewer’, this project will help to improve the quality of the River Thames, as well as making sure the site is ready to handle the expected increase in London’s population in the future.”
Declan McGeeney, Laing O’Rourke’s head of infrastructure, UK, said: “Six years ago, we delivered a substantial upgrade to Beckton and we’re delighted Thames Water has trusted us to return.
“The project will maximise the use of digital engineering and off-site manufacture, with every detail of the works being built virtually before the real thing.
“Many of the tanks, such as the walls of the new activated sludge plant, will be built at our factory in Nottinghamshire before being transported for assembly on site.
“These modern methods of construction help us to deliver six months faster than traditional methods would allow.”