Seasonal influenza is a respiratory infectious disease caused by influenza A viruses (subtypes A(H1N1)pdm09 and A(H3N2)) or influenza B viruses. In mainland France, as in all countries with a temperate climate, it causes an epidemic every year during the winter season, generally between December and March, while this seasonality is less pronounced in intertropical zones, including in France’s overseas regions and departments. Seasonal influenza epidemics vary substantially from year to year in terms of the viral strains involved, timing, magnitude, and severity. It is therefore very difficult to predict their impact in advance. This report details influenza surveillance data for the 2011–2012 to 2021–2022 seasons, focusing solely on data from metropolitan France derived from the national influenza surveillance network coordinated by Santé publique France. On average, per epidemic during the study period, surveillance data in metropolitan France recorded more than 1 million outpatient visits, more than 20,000 hospitalizations, and approximately 9,000 influenza-related deaths, concentrated over an average epidemic duration of ten weeks, with significant variations from one epidemic to another and by age. These figures underscore the considerable impact of seasonal influenza on public health. It is also important to note that data from outpatient care and hospitalizations significantly underestimate the actual burden of seasonal influenza.