The number of short-term residential lettings in London has surged fourfold to 80,770 homes, up from 18,440 in April 2015.
Research from the Greater London Authority found the number of listings had grown in all boroughs, at May 2019.
The biggest increase was in Westminster, rising to 9,062 listings, up from 2,421 four years earlier, making it the borough with the most short-term lets.
It was followed by Tower Hamlets with 7,752 listings and Camden at 5,685.
Last month, London Councils called for more regulation of the booming short-term lets market. It estimated that one in 50 London homes was being let on a short-term basis, equating to 2% of homes.
However, the GLA research found the proportion of short-let homes in central London boroughs is more than twice this.
It found the number of entire-home listings as a proportion of total dwelling stock was 5.4% in Westminster, 5.3% in Kensington & Chelsea, and 3.2% in Tower Hamlets.
The report said 40% of the listings had not been reviewed in the past year and could be considered inactive, estimating some 48,100 active listings.
Westminster also had the highest number of active listings at 5,850, followed by Tower Hamlets at 4,700 and Camden at 3,630.