The Mayor of London has dropped plans to close ticket offices at 51 London Overground stations.
Busy stations will continue to operate as usual, though many will have opening hours reduced to just two-and-a-half hours per day, City Hall said.
Plans to shut dozens of ticket offices across the network were announced last year, amid protests from unions.
An additional £5m funding from London's business rates has been made available to keep offices open, Sadiq Khan said.
From this amount, £1m will be invested in new technology to improve stations, including remote-controlled ticket barriers and trials of video-link ticket machines this summer.
All stations will continue to have staff on the premises from 15 minutes before the first train of the day until 15 minutes after the last train leaves.
At quieter stations, ticket offices will be open a minimum of 0730-1000 Monday to Friday.
Ticket offices at Stamford Hill and Theobalds Grove, which are currently not functioning, will not be re-opened.
Transport For London (TfL) are in discussions over whether White Hart Lane will be redeveloped without a ticket office.
Arriva Rail London, who won a £1.5bn contract to operate the London Overground in March 2016, said it will "continue to work with employees and unions on the wider modernisation programme".
Mr Khan said: "I have asked TfL to ensure that no ticket officers will be closed permanently.
"I am proud of the service the London Overground provides to hundreds of thousands of Londoners every day."
TSSA General Secretary, Manuel Cortes, said: "It's not just trade unions who were in this fight. The people of London were at the heart of overturning the proposal to take away ticket office staff.
"We want Sadiq to build on that mandate and now pledge to restore staff and ticket offices across the Overground and Underground networks."