Childhood overweight and obesity are public health concerns, with rising prevalence observed across many countries. Several factors are linked to this trend, including exposure to antibiotics. While recent studies suggest a potential link, few data exist for children older than two years old, and none have been conducted in the French population.Investigating the association between antibiotic prescriptions during general practitioner consultations and the onset of overweight or obesity among French children aged 2–17 years.A retrospective cohort study was conducted using data from the French primary care database XXXX (2012–2022). Children aged 2–17 with an initial BMI classified as normal were included. Antibiotic exposure was assessed both as the average annual number of prescriptions received and as the absolute number of prescriptions. The main outcome was the onset of overweight or obesity (IOTF criteria). Relative risks (RRs) were estimated using quasi-Poisson regression models, adjusted for sex, age, and medical centres.Among 8,353 included children (47,054 person-years), 1,026 developed overweight or obesity. A significant dose–response relationship was identified in the trend analysis between the mean annual number of antibiotic prescriptions and the onset of overweight or obesity (RR = 1.20; 95% CI: 1.11–1.29; p < 0.001), indicating a 20% higher risk for each additional antibiotic prescription per year.  When considering the absolute number of antibiotic prescriptions between ages 2 and 4, a significant association was also observed (RR = 1.09; 95% CI: 1.03–1.14; p < 0.001). Both high and non-high ecological impact antibiotics were implicated.Although antibiotics are often essential in paediatric care, this study from a real-word database found a significant dose–response association between antibiotic exposure and the development of overweight or obesity in children aged 2-17 years. These results align with previous epidemiological studies, biological plausibility, and veterinary evidences of antibiotics used as growth promoters. It represents the first evidence from French primary care.These findings strengthen concerns that antibiotic exposure may contribute to overweight and obesity during childhood. They support the need for strengthened antibiotic stewardship in primary care and further evaluation of modifiable risk factors for overweight and obesity.