The school meal system could contribute to the transition towards more sustainable food system by promoting plant-based meals. Knowing whether parents want more vegetarian school meals for their children is a prerequisite for a successful implementation. The present study aimed to estimate the proportion of parents who would opt for more vegetarian school meals for their children and to study associations of willingness with family characteristics and food choice motives. An online survey was sent to parents whose children are registered for school canteen in Dijon (France). We collected child-level information, data on family sociodemographic characteristics, and data on dietary habits and food choice motives of the family. We examined family characteristics associated with the willingness to increase the frequency of vegetarian school meals from one meal per week to two or daily. Generalized linear models were performed. In total, 49% of parents were willing to opt for a second weekly vegetarian meal and 26% for a daily vegetarian meal for their children (n = 1261). Parents willing to opt for more vegetarian meal were more likely to have higher education, be flexitarian or vegetarian and to currently opt for pork-free meals for their children, and their children attended the school canteen less frequently. Environmental motives were positively associated with the willing to opt for a second weekly vegetarian meal; familiarity and sensory appeal motives were negatively associated. Health and animal welfare motives were positively associated with the willing to opt for a daily vegetarian meal and sensory appeal was negatively associated. Increasing the frequency of vegetarian school meals would satisfy a demand expressed by parents but must be accompanied by interventions enhancing pleasure of eating vegetarian meals.