Background and aims: Tobacco use is a leading global risk factor for premature mortality. Cannabis-related harms are well documented, and its co-use with tobacco may hinder smoking cessation efforts. Moreover, tobacco use may amplify certain cannabis-related harms. To inform targeted interventions, we provided estimates of tobacco and cannabis co-use prevalence and correlates in France. Methods: Using data from a 2021 nationwide representative sample of French population aged 18–64 years, we estimated the prevalence of tobacco and cannabis co-use. Co-use was defined as reporting daily cigarette smoking and at least monthly cannabis use. We used multinomial logistic regression models to identify factors associated with co-use. Results: Among the 18,288 study participants, 71.8 % reported no use of cannabis or tobacco ('no-use' group), 22.3 % tobacco mono-use, 1.4 % cannabis mono-use, and 4.5 % co-use of both substances. Individuals who co-used reported a more frequent cannabis use than those who mono-used cannabis. Having financial difficulties was significantly associated with co-use, compared to tobacco and cannabis mono-use. After multivariable adjustment, the odds of co-use compared with 'no-use' was 2.3 times higher for participants with a poor health status, and 3.0 times higher for those with financial difficulties. Reporting a major depressive episode and unhealthy alcohol use were also significantly associated with co-use. Conclusions: The clinical management of individuals who co-use tobacco and cannabis should include comprehensive assessments of physical and mental health, as well as alcohol consumption. Interventions to reduce co-use-related harms should also address the adverse social conditions experienced by this population.