Flu vaccination coverage among older adults has declined in France in recent years. The objective of this study was to assess the impact of seasonal flu vaccination on winter mortality among people aged 65 and older. Three types of data were used to estimate the annual number of deaths prevented by vaccination among people aged 65 and older: an estimate of the influenza vaccine’s effectiveness against all-cause mortality, mortality data in France, and vaccination coverage data. We estimated that approximately 2,500 deaths were prevented each year through vaccination during seasonal influenza epidemics between November 2000 and April 2009, and that the vaccine was 35% effective in reducing influenza-related mortality. While vaccine efficacy is lower among those aged 80 and older (27% versus 49%), the number of vaccinations required to prevent one death is lower than among those aged 65–79 (approximately 1,400 versus 4,500) due to a mortality rate that is six times higher. Assuming identical epidemics, 500 deaths would have been prevented if vaccination coverage in 2014–2015 had remained at the average levels observed between 2000 and 2008. Such results could help restore confidence in influenza vaccination among at-risk populations.