From November, school canteens will provide one vegetarian menu each week as a matter of routine.
Education officials are keen to reassure parents that the meals will remain balanced and nutritious, with meat proteins replaced by those found in vegetables and pulses.
Children eat two to four times as much meat as they should, according to the regional food safety agency.
In Rouen, meat-free meals have been available daily since the start of the school year following a trial in April.
Officials said the greatest resistance to the change came from parents, rather than children.
Forty per cent of pupils in the city have signed up for the new menus.