The Child Poverty Action Group (CPAG) said the figures released by the Department for Education, underline the need for a greater effort to reduce poverty in the capital.
According to the data, Tower Hamlets has the highest percentage of secondary students taking up free school meals at 45.9, followed closely by Islington, Westminster, Southwark and Newham.
CPAG said this reflects findings from the End Child Poverty campaign’s child poverty map published in March.
"This data reflects the reality of where child poverty is and while it is a nationwide problem there is a particular issue in London," CPAG’s head of policy Imran Hussein said.
"One of the disappointing elements of the government’s child poverty strategy published in April, was the lack of an adequate London focus. If the government is going to meet its child poverty targets it is going to have to tackle child poverty in London."
Hussain also stressed that all children eligible for free school meals are supported to take them up so they have one healthy meal a day and to help family income.
"Free schools matter. Local authorities can do more to work together to improve the registration of parents whose children are eligible for free school meals.
"There are issues around stigma, but some schools get around that by having, for example, a swipe card system, but others still have old systems of tickets or even different queues."
Meanwhile, Isobel Cattermole, corporate director of children, schools and families at Tower Hamlets Council, stressed the benefits to pupil performance from having access to healthy school meals, adding: "The academic performance of children eligible for free school meals in Tower Hamlets is continuously improving.
"Additionally, the academic achievement of the borough’s pupils who are eligible for free school meals is much more aligned with the achievement of those young people who are not eligible for free school meals, when compared with other areas of London and nationally."
