The work at Tooting station began in spring 2023 and was completed in January.
Following final testing, the lifts are now fully open.
Each new lift provides step-free access to each platform from the main entrance of the station and down to platform level.
In addition, the project team installed new CCTV cameras to enhance the security of the station, as well as widening footways.
Thameslink has also invested £57,000 to put in a wide ticket gate for wheelchair users and people with pushchairs or luggage, and will have soon finished refurbishing the front entrance and entire ticket hall, which includes a new ceiling and improved lighting.
Network Rail’s contractors also enhanced a small patch of land close to the station with new planting for local residents to enjoy.
The station has remained open throughout the work, minimising the impact on how passengers accessed the station.
Lucy McAuliffe, Sussex route director for Network Rail, said: “I’m delighted that we’ve been able to open our latest Access for All scheme at Tooting which will provide step-free access to those in wheelchairs, or with pushchairs or heavy luggage to be able to reach their trains.
“We want our railway to be as inclusive as possible and Access for All is opening up travel by rail to more and more people, with Tooting just the latest station to be completed and more to come across our network over the next few years.”
Govia Thameslink Railway’s customer services director, Jenny Saunders, said: “Everyone at GTR is committed to building a more accessible and inclusive railway, and we’re delighted our passengers at Tooting now have a step-free route to the platforms.
“Lifts benefit everyone who finds stairs a barrier, and for some disabled passengers this project has the potential to be life changing.”