The Congo Basin and its forests store an estimated 65 gigatons of carbon, both above and below ground. Despite rising temperatures and more frequent droughts, these forests have continued to take up more carbon than they release since 1980. However, major gaps remain in how we measure carbon uptake, release, and transport across the region, making it difficult to assess the Congo Basin’s role in the global carbon cycle and its future as a carbon sink. Our review summarizes current knowledge on how climate change and human activity are affecting carbon dynamics. We find that long-term changes in temperature and drought are reducing carbon stocks and uptake, while changes in rainfall have had limited impact. Deforestation, farming, and logging are reshaping forest structure, changing animal-ecosystem services, and reducing carbon storage. Fires in nearby savannas deliver nutrients to forests. Rising CO₂ may improve plant water-use efficiency, but its effect on long-term carbon gains is still unclear. Past climate and land use likely shaped today’s forests, but their influence is not fully understood. Better satellite data, on-the-ground monitoring, and long-term measurements are needed to track how climate and land use are reshaping the Congo Basin’s vital carbon stores.