Clapham Junction station is said to be one of London’s busiest interchanges.
Part of a £35m investment programme, works under the second phase will include the remodelling of the Brighton Yard entrance at bridge level off St John’s Hill.
It will enable the deployment of wider gatelines to enhance accessibility and lower congestion.
More space will be constructed to accommodate five new retail units, including coffee shops and newsagents.
Other improvement works include the construction of toilets, and baby changing facilities for passengers, including those with restricted mobility.
These upgrades are expected to cost £15.5m.
In December, Network Rail will begin the third phase of work to replace and widen the current staircases on platforms 13 and 14.
The aim is to enhance safety and enable more people to pass through at once.
Network Rail senior sponsor Adrian Gogay said: “Clapham Junction station is one of London’s busiest interchanges, situated at the heart of South West London, and we believe it needs to be given some love to make it a more pleasant and enjoyable experience for passengers who are travelling to and from it.
“We welcome the major investment from the Department for Transport and are working closely with our partners to help improve and grow the station to make it more comfortable for passengers when travelling.
“So far, our teams have completed a series of improvements, including installing and rolling out free passenger WiFi, refurbishing the lifts to improve accessibility, and repainting the overbridge from platform one to six.”