Surface coal mining accounts for about 40% of global coal production, and is notorious for its myriad environmental problems and associated social issues. The Mongolian Plateau, consisting of Inner Mongolia of China and the sovereign state of Mongolia, is the world's largest surface coal mining region, producing more than 13% of the total global coal. This study represents the first comprehensive assessment of the spatial extent, expansion rate, and environmental and economic impacts of surface coal mining across the entire plateau, based on data mainly from remote sensing imagery, field surveys, and governmental documents. Our results show that during 1975-2015 the total number of surface coal mines increased from 516 to 10,834 (up 21 times), while the total coal-excavating area expanded from 20.77 to 683.92 km² (up 33 times). More than 90% of coal mining occurred in Inner Mongolia in 2015. Surface coal mining in the Mongolian Plateau destroyed or damaged more than 10,000 km² of natural vegetation and agricultural land, and consumed more than 2,315 million m³ of surface water and groundwater, profoundly transforming landscapes with long-lasting impacts on biodiversity, ecosystem processes, and ecosystem services. In addition, rapidly increasing economic inequality raises concerns with social injustice. Policy interventions are needed to stop the rampage of coal mining and promote clean energy-based economic development. Such actions are critical not only for sustaining the Mongolian Plateau, but also for the world to meet emission reduction goals to avert severe environmental and socioeconomic damages of global warming in coming decades.