Secondary forests (SF) have a large climate mitigation potential, given their ability to sequester carbon up to 20 times faster than old-growth forests. Environmental variability and anthropogenic disturbances lead to uncertainties in estimating spatial patterns of SF carbon sequestration rates. Here we quantify the influence of environmental and disturbance drivers on the rate and spatial patterns of regrowth in the Brazilian Amazon, by integrating a 33-year land cover timeseries with a 2017 Aboveground Biomass dataset. Carbon sequestration rates of young Amazonian SF (<20 years old) are at least twice as high in the west (3.0±1.0 MgC ha-1 yr-1) than in the east (1.3±0.3 MgC ha-1 yr-1). Disturbances reduce SF regrowth rates by 8–50% (0.6 – 1.3 MgC ha-1 yr-1). We estimate the 2017 SF carbon stock to be 294 TgC, which could be 8% higher by avoiding fires and repeated deforestation. Maintaining the 2017 SF area has the potential to accumulate ~15 TgC yr-1 until 2030, contributing ~5% to Brazil’s 2030 net emissions reduction target. Supporting SF and old-growth forests conservation alongside the expansion of SF in deforested areas is therefore a viable nature-based climate mitigation solution.