Jamie Oliver is among more than 30 food campaigners calling on the government to act on its promise to prioritise children's health and wellbeing.
Led by charity School Food Matters, the organisations say the Department for Education must look at how schools can support children to stay healthy.
They say that, although the government proposed a healthy schools rating scheme in its 2016 childhood obesity plan, it is still on the DfE's to-do list.
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School Food Matters surveyed 987 parents, governors and teachers about their thoughts on the scheme and how it should be implemented.
The charity's founder, Stephanie Wood, said: "Quite simply, we conducted this survey to tell us what we, as school food campaigners, already know: that the healthy schools rating scheme is needed to help schools keep good food on the menu."
The organisation has released a report, supported by Jamie Oliver, outlining the findings and calling for DfE action.
It found that 97 per cent of those questioned were in favour of the scheme, and 85 per cent said it should be made mandatory.
When asked if Ofsted should monitor the scheme, 72 per cent of all respondents agreed, and 76 per cent of the 543 parents agreed.
Ms Wood added: "With children spending 190 days at school, we have a unique opportunity to model good eating habits and teach them how to keep themselves healthy.
"The DfE must act now and use the healthy schools rating scheme, together with the new Ofsted framework, to make sure we're making the most of this opportunity."
Some of the 36 organisations calling for the implementation of the scheme include Action on Sugar, Children's Food Campaign and the mayor of London.
A DfE spokesperson said: "Schools already do an enormous amount to support children to keep themselves healthy and we are introducing health education universally in school from 2020 to teach young people about healthy eating, what constitutes a healthy diet and how to prepare a range of healthy meals.
“We are committed to delivering a healthy schools rating scheme, which will recognise and encourage schools’ contributions to preventing obesity by helping children to eat better and move more.
"We are continuing to work with partners on the detail of this scheme to make sure it is effective for every school.”