From July 24 to September 9, 2024, France hosted the XXXIII Summer Olympic Games and the XVII Paralympic Games (OPG), attracting visitors from around the world. With simultaneous sporting and festive events taking place in the middle of summer, hosting the OPGs posed a major challenge in terms of public health safety. This report summarizes the work carried out by Santé publique France, the National Public Health Agency, in collaboration with the Ministry of Health and various national and international public health stakeholders, for the surveillance and prevention of health risks. This work leaves a valuable legacy, such as the development of new surveillance systems and new partnerships. This sharing of experience is intended for anyone interested in public health safety in the context of large gatherings.