Abstract: The global mining industry is currently being challenged by increasing mining depths, more complex geological conditions, stricter environmental regulations, and the urgent need to transition toward low-carbon and sustainable development. Therefore, safe, efficient, and environmentally responsible exploitation of metal mineral resources has become essential for ensuring stable strategic mineral supply chains and supporting future energy systems. National policies and development plans of China emphasize the need to advance deep-resource extraction technologies, green mineral processing, and integrated mining systems with higher resource utilization efficiency while reducing environmental impacts. However, the conventional “mining–surface transport–centralized mineral processing–tailings disposal” production model faces limitations in deep underground operations. These limitations include poor coordination between production stages, extensive material hoisting and transportation, high energy consumption and carbon emissions, increased operational costs, and long-term environmental and safety risks associated with surface tailing storage facilities. Integrated mining, processing, and backfilling (MPB) technologies have emerged as promising development pathways for deep underground metal mines. This paper systematically reviews the theoretical evolution, key technological advances, representative engineering practices, and future development trends in underground MPB systems. It further analyzes the historical development of this concept—its evolution from isolated underground pre-concentration practices aimed at reducing transportation costs to a comprehensive system engineering framework that integrates mining, mineral processing, waste management, and intelligent control. Furthermore, it examines the coupling among mining operations, underground preconcentration, short-process mineral processing, solid waste utilization, backfilling technologies, and intelligent scheduling systems. From a systems perspective, MPB integration extends beyond combining individual technologies to the coordinated management and dynamic optimization of ore, solid-waste, information, and safety-risk flows within constrained underground environments. This paper summarizes the recent progress in several critical technology areas, including precision blasting and fragmentation control, continuous crushing and intelligent transportation systems, underground ore sorting and pre-concentration, short-process beneficiation technologies, multisource tailings, waste rock collaborative utilization, underground paste preparation and backfilling systems, modular equipment deployment, digital twins, and intelligent scheduling technologies. These developments collectively provide a technical foundation for transforming traditional linear mining processes into integrated underground production systems characterized by source reduction, resource recycling, and coordinated operations. Analysis of international and domestic engineering practices indicates that MPB technologies are gradually transitioning from parallel application of individual technologies to system-level integration, supported by intelligent control and digital management. However, its large-scale implementation remains constrained by several critical challenges, such as limited underground space, harsh deep-mining environments, equipment reliability issues, insufficient understanding of cross-process parameter interactions, physicochemical coupling between preconcentrated tailings and backfill materials, long-term stability and environmental performance of in situ solid-waste utilization, and the absence of unified system-level models and decision-making frameworks. Future research should focus on establishing quantitative parameter transfer mechanisms linking blasting fragmentation, crushing products, preconcentration performance, tailing characteristics, and backfill behavior. Additional priorities include developing applicability assessment criteria, dynamic scheduling and optimization models, low-carbon functional backfill materials, digital-twin-driven control systems, and life-cycle safety and health-monitoring frameworks. Ultimately, MPB systems are expected to evolve into fully integrated, intelligent, low-carbon, and safety-oriented mining paradigms. This review provides a comprehensive theoretical and technical reference for advancing integrated mining, processing, and backfilling technologies and promoting their application in deep underground metal mines.