Introduction – Lack of physical activity (PA) and a sedentary lifestyle are two risk factors for many noncommunicable diseases. Regular monitoring of these behaviors among the general population is necessary to assess their impact on health and tailor prevention policies to the population’s needs. Method – This article presents the levels of PA and sedentary behavior among the adult population in France in 2021, based on the results of the 2021 Santé publique France Barometer (mainland France and overseas departments and regions), as well as the associated sociodemographic factors. The scale of these surveys makes it possible for the first time to estimate these prevalences at the regional level. Results – In 2021, 73% of men and 59% of women met the PA recommendations. The prevalence of meeting the additional recommendations for muscle-strengthening activities was 31% among men and 20% among women. More than one in five adults reported spending more than seven hours a day sitting, and the prevalence of leisure screen time exceeding three hours daily reached 39%. Only the recommendation to break up sedentary time appeared to be well followed. Compliance with PA recommendations was associated with sex, age, educational level, and urban area size, as well as employment status for men and household structure for women. Sedentary behavior was associated with age, educational level, urban area size, household structure, and employment status. Compliance with PA recommendations varied by more than 15 percentage points across regions. Brittany and Occitanie stood out with a prevalence significantly higher than the national average, in contrast to Île-de-France and the Northeast of France, which had prevalences significantly lower than the national average. Conclusion – These data provide an overview of physical activity levels and sedentary behavior among adults in France in 2021 and identify the populations and regions that should be prioritized for prevention efforts.