Abstract: The mining of coal under buildings has always been a major technical challenge for coal mines. To address this issue in China, the bedding separation grouting subsidence reduction experiments were carried out from the 1980s in about 10 coal mines, achieving certain results. However, since the actual subsidence reduction rate did not meet the requirements for building protection, the technical feasibility of mining coal under buildings through bedding separation grouting was questioned and gradually abandoned. Based on the key stratum theory of strata control and the full-stratigraphy academic thought, the overburden isolated grouting technology was developed. It was first successfully applied in Huaibei mining area in 2009, solving the problem of mining coal under buildings. Its application scope, scale, and fields have been continuously expanding. Currently, the enthusiasm for overburden isolated grouting is on the rise. To promote the healthy development of the industry’s technology, it is necessary to scientifically review and comprehensively examine the development process, and clearly define the differences at the theoretical and technical levels. This innovations of overburden isolated grouting in theory, technology, and practice are systematically discussed. At the principle level, it clearly shifts the technical essence from the “searching for bedding separation” of bedding separation grouting to the “compaction grouting” of isolated grouting, firmly establishing the correct guiding ideology and theoretical direction. From the perspective of the cumulative effect of unloading and expansion of the overburden due to mining, it is found that the bedding separation is suppressed, and the maximum amount is usually less than 10% of the mining height. In some conditions, there is even no bedding separation. Bedding separation grouting focuses on the “bedding separation space” and fills it, which has been proven to have a small filling volume and a low grouting-to-mining ratio, and is difficult to prevent the key stratum from breaking and sinking. This is the fundamental reason why the subsidence reduction effect of bedding separation grouting is not as expected. The compaction grouting method of overburden isolated grouting changes the passive “searching for bedding separation” to the active “creating space”. Through the “lifting up and pressing down” effect of grouting pressure, the unloading and expansion strata below the key stratum are re-pressed before its breakage and sinking, thereby generating a grouting space, significantly increasing the grouting-to-mining ratio, and forming a compacted support structure in the middle of the goaf, which provides support to the key stratum structure and maintains long-term stability. Based on the principle innovation, the technical level has overcome three major problems: where to grout, how much to grout, and how to grout, transforming the abstract theory of compaction grouting into a process method. In terms of grouting layers, the concept of the main layer position was innovatively proposed, fundamentally ensuring the subsidence control effect of grouting. Through the application of theoretical methods such as the prediction of the height of the fracture zone based on the position of the key stratum, the isolated layer and safety of grouting were ensured. Especially under the guidance of the full-stratigraphy academic thought, in the condition of thin bedrock and thick unconsolidated layer, the overburden structure shifts from the key stratum of the bedrock to the arch structure of the unconsolidated layer, the grouting layer of overburden isolated grouting has evolved from the bedrock to the bottom boundary of the unconsolidated layer, and practical innovations have been achieved. Focusing on the key technical issues of filling volume and grouting-to-mining ratio, the theory clarifies the process from solid slurry to liquid slurry and then to compacted consolidation of filling materials, and determines the spatial trapezoidal state of the filling body based on the movement law of strata. A formula for calculating the grouting-to-mining ratio considering rock mass expansion and surface subsidence is proposed, fundamentally answering the questions of how much can be grouted and how much needs to be grouted, and completely overturning the cognition of estimating the filling volume based on the bedding separation volume. Furthermore, a grouting control technology centered on grouting-to-mining matching is proposed, transforming compaction grouting into controllable guided grouting, ensuring the subsidence reduction effect from the source. Coupled with a series of design methods for grouting borehole layout and the application of monitoring and regulation of parameters such as grouting pressure, density, and flow rate, the long-term healthy operation of grouting through boreholes in the mining-induced black box strata and the stability of surface subsidence control effects have been achieved. Supported by a series of theories and key technologies, overburden isolated grouting has increased the grouting-to-mining ratio to over 50%, and controlled the surface subsidence coefficient below 0.1, meeting the requirements for buildings protection. It has achieved the mining without relocation of villages (subsidence reduction), the comprehensive utilization of millions of tons of coal-based solid waste (emission reduction), the protection of aquifers (leakage reduction), and the prevention of mine earthquakes (vibration reduction). The development direction is to address the shortage of solid waste filling materials in coal mines and the “dual carbon” goals by using CO₂ as grouting material to achieve the “one injection, five reductions” effect of subsidence reduction, emission reduction, leakage reduction, vibration reduction, and carbon reduction, and realize green mining and low-carbon utilization of coal resources.