<p>The Brazilian Atlantic Forest is a global biodiversity hotspot that harbours a high number of endemic species and provides important ecosystem services. However, a long history of deforestation means that only 24% of its original forest cover remains and studies are needed to examine the spatial and temporal patterns of forest loss to better understand the effectiveness of current laws in curbing deforestation in this important biome. Here we provide a comprehensive quantitative and qualitative time-series analysis of mature forest loss within the Brazilian Atlantic Forest. From 2010 to 2020, we detected 14,401 deforestation polygons, resulting in a loss of 186,289 ha, most of it with a high likelihood of illegality. These losses occurred mainly in small-sized patches on private lands for agricultural expansion, but also in protected areas and Indigenous lands. Deforestation is concentrated in two hotspots that involve different agricultural actors and land-use change processes. This pattern could lead to species extinctions, ecosystem service losses and a weakened capacity to address climate change, thus challenging the effectiveness of mechanisms currently used to counter deforestation. Implementing further incentive, protection and enforcement measures could aid in progress towards zero deforestation in this critically important habitat.</p>