Transitioning away from fossil fuels poses significant challenges for coal-dependent workers and regions. While anticipating job losses is crucial for designing effective policy responses, we examine the future of coal workers across time and geographies in China and India under mitigation scenarios. We focus on mine workers who have been less studied, outnumber those in coal power plants, and are more geographically concentrated. Our approach enriches the results of an integrated assessment model by incorporating mine-level data and coupling with a novel module for demographic and labour mobility to understand how concentrated vulnerabilities challenge the transition. A decline in coal jobs is inevitable in China due to continued mining productivity increase. The potential employment reduces by 41% in the next decade even under current climate policies. On the other hand, India faces a critical crossroads as projected mining production growth surpasses productivity increases. Beyond national climate ambitions, differences in mining productivity, local economic diversification, labour concentration, and employment patterns drive subnational disparities in vulnerability to accelerated mitigation. Notably, Shanxi and Jharkhand, the main mining regions for each country, account for a third of the 1.2 million workers who may struggle to transition to other sectors in the next decade under ambitious emissions mitigation. Although they are less exposed with a smaller mining workforce, the challenges for unproductive regions such as West Bengal or Shandong are even more urgent. Our findings provide quantitative insights to guide just transition policies, emphasising the need for targeted support, including transitional assistance and economic diversification, in the most affected coal-producing regions.