The objective of this article is to describe the temporal and geographic variations in participation rates in the national organized breast cancer screening program since its expansion to the entire French territory in 2004–2005, by examining recent trends at the national, regional, and departmental levels. The participation rate is defined as the number of women aged 50 to 74 who underwent screening during each study period, as reported by the regional cancer screening coordination centers, relative to the target population data from the National Institute of Statistics and Economic Studies. Participation in this program is low in France and has been declining since the early 2010s. It has been impacted by the recent pandemic. Nationally, after rising through 2012 to peak at around 52%, participation declined to 48.5% in 2019. During 2020, it fell to 42.6%, then rose to 50.6% in 2021. While participation in 2021 partially offset the shortfall from 2020, participation for the 2020–2021 period remains lower than that of the 2018–2019 period. At the regional level, a geographic gradient has been observed since the program’s implementation, with the highest participation rates along an axis stretching from Brittany to the Auvergne-Rhône-Alpes region and very low participation in Île-de-France and the Southeast. In France, despite the existence of an organized breast cancer screening program, mammograms can also be performed outside of it, but this activity is difficult to measure. In this context, there is an urgent need for reliable data to quantify screening practices outside the program in order to obtain a comprehensive overview of overall breast cancer screening uptake, both in terms of temporal and geographic variations.