Network Rail has awarded a contract to Vinci Construction for the design and upgrade of 13 train stations in west London and Berkshire.
The improvement works will concentrate on the Acton Main Line to Maidenhead, with many of the stops being overhauled in preparation for Crossrail.
As well as new buildings and ticket halls, lifts are also being installed so longer platforms can be accommodated.
Speaking about the deal, Crossrail's surface director Matt White said: "For the residents of west London and Berkshire, Crossrail will bring new trains, better stations and quicker journeys."
He added the scheme is on target to deliver "significant benefits to passengers".
The work is not scheduled to get underway until the mid point of next year and will be completed by the end of 2018.
Network Rail also announced Balfour Beatty will electrify the overhead line from Airport Junction and Maidenhead across all tracks.