The "living wage" rate for London, which is calculated on the cost of living in the capital, has been increased to £8.80, a rise of 25p.
The London Living Wage, which is not binding on employers, was also increased last year, to £8.55 per hour.
Since it was introduced in 2005, 214 employers have signed up. The National Portrait Gallery, Pearson and Oxfam are the latest.
The living wage rate in the rest of the UK was also raised, by 20p to £7.65.
The new rates were announced at the start of Living Wage Week. The minimum wage for the UK remains £6.31 per hour.
'Need more converts'
Mayor Boris Johnson said: "Paying the London Living Wage ensures hard-working Londoners are helped to make ends meet, providing a boost not only for their personal quality of life but delivering indisputable economic dividends to employers too.
"This in turn is good for London's productivity and growth. It is extremely heartening to see major new companies signed up this year but we need more converts."
The wages of up to 19,000 people have been affected by the scheme and a further 90 employers in the capital are waiting for accreditation, the mayor's office said.
London Assembly Labour Group Economy spokesperson Fiona Twycross has called for a statutory status for the London Living Wage.
She said: "At the current rate of progress it will take 450 years for all workers to be paid a living wage in London.
"Should further incentives not work then the legal minimum wage must be set at the level of the living wage."
Jenny Jones, Green Party London Assembly member, said "a few living wage zones won't help".
"The mayor needs to tackle the big businesses and government departments that can afford to pay a living wage," she said.
Liberal Democrat London Assembly Member Stephen Knight said a "tiny fraction" of firms had signed up to pay the London Living Wage, adding: "We can afford no complacency at City Hall on this issue."