Housing minister Brandon Lewis welcomed the law change, which brings the capital into line with the rest of the country.
He said the measures, introduced in the last Parliament, will free homeowners from the “bureaucratic headache” of applying for planning permission just to rent their home out for a few weeks.
Thousands of properties in the capital are rented out on a short-term basis through sites such as AirBnB, OneFineStay and Gumtree.
But until today London homeowners looking to rent their properties out for up to 90 nights would have had to apply for planning permission – under laws dating back to the 1970s.
Those who failed to do so could have faced a fine of up to £20,000 for each unlawful rental. But changes to the law coming into force today alter that, and put London on the same footing as other towns and cities in England.
Now Londoners looking to rent their home out for up to 90 nights a year can do so without seeking permission from their council.
Today’s rules mean short-term letting of homes is now allowed to a maximum 90 nights in a calendar year, putting London on the same footing as other English towns and cities.
Until today these rentals were potentially in breach of outdated 1973 Greater London Council laws requiring Londoners to get planning permission for rentals of fewer than 90 nights, or face a fine of up to £20,000 for each unlawful rental.
This law, which was poorly and confusingly enforced across the capital, has now been amended by the Deregulation Act, whose provisions on short term lets come into force today.
Housing and Planning Minister Brandon Lewis said: "These outdated and needless rules that restricted London homeowners in what they could do with their home have now been swept away.
"Londoners should be able to use their homes for short term lets without the bureaucratic headache of getting planning permission from the council – just like everywhere else in the country.
"Today’s changes will allow them to earn extra money, increase choice for visitors and bring the capital’s short term rental market up to date with the internet age."