Sadiq Khan said this will bring the total number of step-free access stations on London Underground to more than 100 stations and 40 per cent of the network. The current level is at 26 per cent.
As part of Transport for London's (TfL) draft business plan, it has committed to making over 30 additional Tube stations step-free by 2021-2022. Work will also progress at Bank and Elephant & Castle.
"As part of making London's transport system one of the very best in the world we must ensure it is accessible for all Londoners," Khan said. "It's simply not right that for people with disabilities, parents with young children and many older people, many of our stations are still very difficult to use."
TfL is also bringing forward the delivery of step-free access at outer London stations at Harrow on the Hill and Newbury Park, with work beginning next year.
Ruth Owen, chief executive of non-profit Whizz-Kidz which supports disabled young people through mobility equipment, welcomed the news and the mayor's "clear commitment" to making the city more inclusive.
"Public transport is a lifeline for disabled people, but we know that accessibility can be a major barrier for wheelchair users who, like anyone else, just want to get from A to B," she said.
Faryal Velmi, director of Transport for All, said: "We look forward to 30 more stations being made step free over the next five years as this will unlock parts of the Underground that have been unusable for us since the Tube was created. A more accessible Tube will mean more travel options and greater opportunity for us to enjoy our great capital city."
But Greater London Authority Conservative transport spokesperson Keith Prince said question marks remained over how such significant investment will be funded.
"The mayor has made a very large commitment of £200m at a time when TfL is looking to save over £3.5bn over the next five years," he said. "Following spends of £640m on his fares freeze and another £120m on his Hopper Fare, the mayor is yet to explain where he expects to find any of this additional revenue."
"We all want to welcome good news announcements like this but until the mayor explains how he expects to pay for them there will be a cloud hanging overhead and doubts over whether they can be delivered," Prince added.