Costain, which previously led the scheme through its planning and design stages, will now undertake the improvement works to the interchange between the station platforms and Gatwick International Airport.
Contract award confirmation comes after the secretayr of state for transport, Chris Grayling, signed off on the project yesterday.
Work is expected to begin in early 2020 and is expected to be completed during 2022.
The project will result in a larger concourse, five new lifts and eight new escalators. It will be managed by Network Rail, in partnership with the Department for Transport. Gatwick Airport Ltd and Coast to Capital Local Enterprise Partnership are co-funding the project with £37m and £10m respectively.
The project has already been delayed since 2017 but has become increasingly necessary. The number of people using Gatwick Airport station each year has grown from 14 million in 2010 to more than 20 million last year.
Gatwick Airport chief executive Stewart Wingate said: “Gatwick has been transformed in recent years and the redesigned train station will take the airport’s redevelopment to the next level by providing a seamless transition between the airport and the station, more lifts, escalators and a doubling in the size of the concourse.
“The new station will complement the huge improvements to rail services at the airport, which include new fleets of Gatwick Express and Thameslink trains and services that now leave the airport for London every three minutes – as frequently as services on the tube.
“The project is a fantastic example of the public and private sector working together to deliver a world-class transport hub that will comfortably manage the expected growth in air passengers and also encourage people to switch to rail as part of our push to get more people to travel to the airport by public transport.”
Costain chief executive Alex Vaughan said: “The development at Gatwick will transform the existing station and provide a greatly enhanced experience for airport and passengers. Costain’s extensive capability to deliver complex programmes, using leading edge smart technology, will ensure travellers are kept moving at every stage of the works, minimising disruption during this capacity-critical redevelopment.”
Chris Grayling said: "We want to see Gatwick Airport’s success continue to flourish and ensure that it is ready for even more passengers in the future. Through this £150m investment, we will deliver vital upgrades to boost the station’s capacity and provide better, seamless journeys for all."