Knightsbridge Tube station is next on the list to become step-free, with Transport for London (TfL) announcing it will become more accessible from 2020.
In the process, the £12m upgrade will open up parts of the station that have been closed since the 1930s when escalators were installed.
The transport body is plugging an additional £200m into boosting the accessibility of the capital's stations, in order to take the total number providing step-free access to over 100.
The station, which is used by 19m passengers a year, is undergoing a massive revamp to make travel easier for older and disabled people, as well as for other customers who find it difficult to use the stairs or escalators.
The upgrade comes after the recent completion of Bond Street's upgrade, which also introduced step-free access, taking the total number of step-free Tube stations to 72.
Mayor Sadiq Khan has set a goal for 40 per cent of the network to be step-free by 2022.
Khan, said: “My commitment to making London’s transport network one of the very best in the world means it must be accessible for all Londoners.
"I’m investing record amounts in making London’s stations step-free, and the redevelopment of the famous Knightsbridge Tube station will benefit millions of people every year."
Knightsbridge Tube station is owned by TfL, though the property above the station is owned by the Knightsbridge Estate. The Estate got the green light to redevelop it last year, and will overhaul the office, retail and residential space inside.
For the works to go ahead, the station entrance on the corner of Sloane Street and Brompton Road has closed, and when the revamp is complete, the former entrance space will become a retail unit owned by the Estate.
Knightsbridge has two alternative entrances on Knightsbridge Road, and TfL said the disruption to customers is expected to be minimal while the work goes ahead.
The new station will be open to customers in 2019, with another opening in 2020 at Hooper's Court, providing two lifts. The pavement on Brompton Road and Sloane Street will also be widened to make more space for pedestrians.
Mark Wild, London Underground’s managing director, said:
Improving accessibility across London’s transport network is one of our top priorities so I’m delighted that another of our Zone 1 stations will become step-free.
The work is part of our continued modernisation of London Underground to provide increased capacity and make journeys better for our customers. A fully accessible Knightsbridge station will give a greater choice of travel options for everyone.