Nearly one worker in five living in London earned less than the capital's living wage in 2013, according to new research.
The think-tank, New Policy Institute, said there were more than 640,000 low-paid jobs in the city last year, compared to 45,000 in 2012.
About 25% of outer London jobs were low-paid with 13% in inner London.
The living wage of £8.80 an hour is based on the amount an individual needs to earn to cover basic costs of living.
The research also found that in 12 London boroughs a quarter or more of jobs were low-paid, reaching 33% in Bexley and Harrow.
The findings suggest the cost of living is growing faster than earnings, reflecting a trend prevalent across England, according to the NPI.
In 2013 about 18% of all London jobs were below the living wage, up from 17% in 2012 and 12% in 2009.
Mubin Haq from the charity Trust for London, which aims to reduce poverty and funded the research, said: "The true measure of a recovery should be what it means for those nearest the bottom.
"With a 7.5% increase in the number of jobs that are low-paid, these new figures suggest that for many poorer Londoners, working hard is not lifting them out of poverty."
Among London's 33 boroughs, Bexley and Harrow had the highest proportions of low-paid jobs and Richmond had the lowest, with 11%.
The wholesale industry accounted for 27% of London's low-paid jobs, while 22% were in hotels and restaurants: a combined total of 49%, up from 45% in 2010.
Low-paid work was most evident among workers of Bangladeshi and Pakistani origin, with 44% of employees earning below the living wage, while among people of Black African origin the figure was 41%.
The lowest proportion of low-paid workers was among people of a White British background.
Most low-paid jobs were done by women, due to the high proportion of part-time work done by women compared to men.