BACKGROUND: Immigrant women often have lower cervical cancer screening (CCS) rates, tend to have a higher body mass index (BMI) and may be more vulnerable to BMI-related stigmatization. Our aim was to assess the role of BMI in differences in CCS rates by migration history. METHODS: Analyses were based on the 2012-2015 inclusion data (n = 27,226) for the population-based CONSTANCES cohort, including detailed, self-reported information on demographics and socioeconomic characteristics, migration history, health behaviours, health, and health care use. Measured BMI (underweight (<18.5), normal-weight (18.5-25), overweight (25-30), obese (>30)) was collected. Poisson regression models with robust variance were conducted to assess the contribution of BMI to differences in CCS rates by migration history, and analyses stratified by BMI were done. Multiple imputations were performed. RESULTS: The CCS rates ranged from 87% among French-born women with two French parents to 86% among French-born women with at least one parent of foreign origin, 82% among naturalized immigrants and 74% among non-naturalized immigrants. After adjusting for covariates, non-naturalized immigrants showed an 11% (95% CI: 8%-14%) lower CCS rate than French-born women with two French parents. Adjusting for BMI did not change the estimates. When stratifying by BMI category, non-naturalized immigrants showed an 11% (7%-14%) lower CCS rate then French-born with two French parents when normal weight, a 9% (2%-16%) lower CCS rate when overweight, and an 18% (5%-30%) lower CCS rate when obese. CONCLUSION: Migration history and BMI jointly impact CCS rates. They were lower among all non-naturalized immigrants, particularly those who were obese.