This means commuters may face a diversion between the Jubilee Line platforms and South Western Railway services.
Network Rail has announced that from August 3, the refurbishment of the escalators at Exit 2 will begin.
This connects the National Rail station to the Jubilee Line and Waterloo Road.
The current escalators are being replaced with “modern, more reliable models” that need less maintenance.
This is part of a wider programme which will see all four escalators replaced this year, starting with the first pair of escalators in August.
The work is expected to take several months, causing potential disruption at the station.
Visitors who are able can use the stairs at Exit 7, on the main concourse, which will add a couple of minutes to their journeys.
A one-way system will be in place during busy commuter times to safely manage crowding.
This might require some passengers to take an alternative route.
Yellow wayfinding signs will direct visitors to the stairs at Exit 7, and the lift will remain in service for those who need it.
Customer service advisors will be available for assistance.
Tom Barry, Network Rail project sponsor, said: “London Waterloo is the flagship station for the Wessex route and the third busiest station in the country, after Liverpool Street and Tottenham Court Road.
“The escalators are in need of repair so we can make this station fit for the future.
“We’re sorry for any disruption our work will cause and thank passengers for bearing with us as we bring you more reliable escalators.”
