Information on the determinants of dietary supplement (DS) use in France is largely lacking, especially in population subgroups such as smokers. Also, little is known about the role of health professionals in DS purchases. The aim of the present study was to describe DS use along with its sociodemographic, lifestyle and dietary correlates in a large sample of French adults (age 18+years) participating in the NutriNet-Sante cohort study. Data were collected by self-administered Internet questionnaires. Food intakes were assessed by 24 h dietary records. Data on DS use were available for 79 786 participants. Supplement users were compared with non-users by logistic regression. Current DS use at least three times/week was reported by 14.6% of men and 28.1% of women. Mg, and vitamins B-6 and C were the most frequently consumed nutrients. DS were prescribed or recommended by a physician in 54.9% of the cases. DS use was positively associated with knowledge of nutritional recommendations and organic product consumption, following a healthier diet and lifestyle (non-smoker, moderate leisure-time physical activity). Current smokers used less DS than did non-smokers, but their DS consumption was substantial (19.0%) and they were more likely to self-medicate. The present study provides updated and detailed information on DS use determinants in a large French cohort, including a focus on smokers, for whom the long-term effects of DS use are poorly documented and could represent a risk. These findings pave the way for future aetiological studies.