Utilities diversion work in south London will start this year ahead of the five-year build programme which will be carried-out in phases.
Network Rail chiefs said the scheme will boost the local economy through the use of local construction workers and trade contractors on the Thameslink project.
Chief executive David Higgins said: “Our work will see the transformation of one of London’s oldest and highly congested railway terminus.
“The London Bridge project is a critical part of the £6bn Thameslink Programme.
“It is only by remodeling London Bridge station that we can allow the new fleet of 12-car trains to operate at a metro-frequency on the Thameslink route. The project will also cover over 46 miles of new track laid in the 4.3 mile approach to the station.
“As well as bringing a better rail service to Southwark, we hope that the construction programme itself will help support the local community.
“How we build is as important as what we build and we are committed to a number of schemes such as local employment, supply chains and community engagement as well as setting up a workplace diversity and inclusion plan.”