Abstract: Coal mine geological assurance is the foundational pillar for safe, efficient coal mining and hazard prevention. Drawing upon the formulation and revision of the Regulations on Coal Mine Geology and the Code for Coal Mine Geological Work, sustained technological innovation, and extensive operational experience from China’s coal industry, this paper systematically reviews the evolution of coal mine geological assurance technologies over the past four decades. The key advances are synthesized into six core aspects: (1) The conceptual framework of geological assurance has evolved progressively—from “coal resource assurance” to “assurance for safe and efficient mining,” and further to “geological assurance for safe, efficient, and intelligent mining”; (2) A multi-generational suite of integrated geological exploration technologies and equipment has been established, spanning surface-to-underground, local-to-regional, static-to-dynamic domains, and integrating drilling with geophysical methods, with representative innovations including underground directional drilling, seismic monitoring during mining or heading (“seismic-while-mining” and “seismic-while-driving”), and long-distance excavation coupled with long-range detection; (3) Proactive, area-wide prevention and control systems have been developed for major geological hazards—including gas outbursts, water inrush, rockbursts, geothermal hazards, and slope failures—tailored to diverse geological conditions; (4) Thirteen categories of concealed geological hazard factors threatening mine safety have been systematically identified, and a comprehensive census framework has been institutionalized under the principle of “all identifiable hazards must be surveyed, periodically reassessed, and dynamically updated”; (5) Geological information representation has transitioned from traditional point–line–plane descriptions to electronic, informatized, and digital formats, culminating in the development of intelligent geological assurance systems centered on the concept of “transparent geology”; and (6) A robust institutional mechanism—featuring well-defined organizational structures, clear responsibilities, and standardized regulations—has been established, promoting the professionalization, standardization, and systematic implementation of coal mine geological work. These advancements have robustly underpinned the remarkable transformation of China’s coal industry: national coal production surged from 0.872 billion tons in 1985 to 4.78 billion tons in 2024; average mine capacity increased from less than 0.1 Mt/a to over 1.4 Mt/a; and the fatality rate per million tons of coal produced plummeted from 7.63 to 0.054. In response to the emerging demands for safer, more efficient, intelligent, and environmentally sustainable coal mining, this paper proposes key development directions including intelligent interpretation of coal mine geological exploration data, ecological geotechnical support for damage-minimized mining, and geological assurance technologies for in-situ utilization of deep coal resources.