Boris Johnson has been promoting London venues on a visit to New York City (NYC), during which the mayor sealed a tourism deal with his counterpart, Michael Bloomberg.
As part of the two-year agreement, the cities will provide each other with advertising space and also share marketing ideas.
Mr Johnson said that London and New York share a strong sense of optimism and determination as well as a belief in diversity and innovation.
"Our common cultural ties, not least absolute dedication to providing world-class services and experiences for both residents and visitors, make the two cities exceptionally well poised to combine knowledge as well as resources," he added.
London will be granted advertising space on 71 bus shelters across New York for four weeks of the year, while the US city will get 250 posters on the Underground for the same length of time.
Earlier this year, figures from the Worldwide Cost of Living, Economist Intelligence Unit survey showed that London was cheaper than New York for the first time since 2002.