More than three million children in England are having school lunches, including just over one million on free school meals, figures show.
An extra 167,000 pupils took up the meals in 2011/12, compared with the year before, data collated by the Children's Food Trust shows.
It is the fourth year running that the numbers have risen.
But the price has also risen - a meal now costs £1.98 on average, compared with £1.93 a year ago.
The figures are based on a survey of local authorities, conducted by the Children's Food Trust.
The survey suggests that, since 2008/09, almost half a million more children have switched from taking packed lunches to school to eating school dinners.
In total, 46.3% of England's primary school pupils and 39.8% of secondary pupils had school dinners this year - the equivalent to 3.3 million pupils.
Trust chairman Rob Rees said: "Our school canteens have the potential to be such power-houses for children's health and their performance at school - as long as schools, cooks and caterers get the support they need to keep this progress going.
"With more of them eating school meals, it's more important than ever to make sure the food they get tastes good, gives them the nutrition they need and that they have an experience which makes them want to go back for more."
A Department for Education spokesman said: "It is encouraging to see that more and more children are opting for a school meal at lunchtime and are being served increasingly healthy and nutritious options.
"This is down to the hard work of schools, local authorities and their caterers, who all know the benefits of a balanced meal on pupils' concentration and ability to learn."
The figures come just two weeks after Education Secretary Michael Gove announced a new review of school dinners, led by Henry Dimbleby and John Vincent, co-founders of the Leon restaurant chain.
It will investigate school dinners across the country, and establish an "action plan" on how all schools can improve food standards.
But the plan was criticised by TV chef Jamie Oliver, who led a campaign seven years ago to improve school meals.
He said it was time for action and not more "costly reports".
A spokesman for the LACA (Local Authority Caterers Association) said: "We cannot afford to allow standards to slip whilst we await the outcome of the Department for Education's latest assessment of food in schools.
"A lack of action now on this issue will increasingly allow poor nutritional habits to creep back in and for the good work to be undone in the intervening time."