Objective To evaluate Lebanese licensed dietitians’ (LDs) knowledge, prevalence of use and recommendation of dietary supplements (DS), and their associated factors. Design Cross-sectional survey. Setting Dietitians across Lebanon were contacted through the telephone and were asked to participate in the study. An online self-administered questionnaire was designed and sent to dietitians either by email or by WhatsApp, between March 4th and May 4th, 2020. Participants This study included 319 dietitians randomly selected from the dietitians’ list that was provided by Lebanese Ministry of Public Health. Results Around 75% of dietitians had a knowledge score above 50%. Overall, 73.7% of them have used DS and 46.1% have recommended them. Higher knowledge score was associated with less years of experience, using scientific articles as source of information on DS, and participating in research. Resorting to pharmacists was significantly associated with both nutrient supplements (NS) and herbal supplements’ (HS) use, whereas referring to health food stores was associated with HS use only. NS recommendation to patients was associated with personal NS use (OR=3.38, P<0.001), considering pharmacists as a source of information on DS (OR=2.29, P=0.01) and discussing DS with patients (OR=3.82, P=0.01). Having personally used HS (OR=12.23, P<0.001) and having discussed DS with patients (OR=8.51, P=0.01) increased the likelihood of recommending HS. Conclusions A proper DS education, the elaboration of national scientific guidelines and the implementation of concise laws regarding the regulations of DS would play a crucial role in supporting dietitians’ practices and improving the quality of patient care with respect to DS.