The scheme first began in Richmond in 2005
Firms in London are being urged to open their toilets to the public, to help tackle a shortage of public lavatories.
Mayor Boris Johnson wants boroughs to sign up the Community Toilet Scheme, where businesses are given grants to open their facilities to the public.
Since 1999 London has experienced the steepest decline in the number of local authority-owned toilets in the country.
The Community Toilet Scheme was first introduced by Richmond Council in south-west London, in 2005.
In Richmond, pubs, restaurants and supermarkets are paid £600 a year to open their facilities to non-customers, giving residents access to a further 75 toilets around the borough.
The facilities are clearly labelled with a badge in the window and some are even signposted from the street.
Councillor Martin Elengorn said: "We are delighted the mayor has singled out our scheme for praise and recommended other councils to consider adopting a similar initiative."
Mr Johnson said: "Older people and families with young children in particular find the lack of public loos inconvenient and an incredible burden when out and about."