Abstract: CO₂ geological storage (CGS) is a key technological pathway for assisting both China and the global community in achieving carbon neutrality goals. Traditional CGS faces the dual challenges of site scarcity and high costs. The realization of a low-cost, large-scale site storage concept urgently requires technological innovation and cross-disciplinary collaboration. Long-term, large-scale, and high-intensity metal mining activities have resulted in vast goafs both in China and globally. While such underground spaces are characterized by shallow occurrence, lack of effective caprock, and poor sealing performance, they possess a significant advantage: high potential for artificial engineering modification. Utilizing them for CO₂ storage would represent both the resource recovery of abandoned underground spaces and an effective supplement to large-scale CGS technological pathways, offering dual benefits. Therefore, this study conducted dedicated research on CO₂ storage methodologies and their feasibility for abandoned metal mine goafs, providing the following conclusions and viewpoints. (a) Drawing on the mature technological model of compressed air energy storage in hard-rock-lined underground caverns, constructing gas storage reservoirs within the drifts and tunnels of abandoned metal mines for physical CO₂ storage is a feasible technical solution. The implementation of this scheme can be divided into two stages: the first stage is the CO₂ reservoir storage–environmental benefit phase, and the second stage is the CO₂ energy storage utilization–economic benefit phase. (b) Based on the concept of backfill carbonation, which utilizes the CO₂ mineralization of industrial solid waste to sequester carbon first and then backfill, thereby achieving goaf disposal and CO₂ storage, this study proposes a synergistic “resource recovery-backfill carbonation” method for abandoned metal mine stopes. This method simultaneously achieves four objectives: expanding carbon sequestration through backfill carbonation, improving resource recovery rates, disposing of solid waste, and preventing geological hazards. (c) The feasibility and key points of applying the Wallula and Carbfix methods for mineralization storage within the goaf–surrounding rock system are discussed for scenarios in which abandoned goafs are surrounded by ultramafic–mafic rock. When the former is used for CO₂ storage in abandoned metal mine goafs, it must still adhere to the sedimentary basin storage paradigm. For the latter, a reliable and economical water supply is the primary prerequisite. (d) Based on the existing CO₂-gangue inorganic framework concept of physicochemical synergistic storage, a method is proposed to achieve such storage within the internal space of abandoned metal mine stopes by constructing artificial traps along their boundaries. The construction of artificial traps enables the parallel implementation of two technological pathways in underground backfill carbonation: “carbon sequestration first, then backfilling” and “backfilling first, then carbon sequestration.” Injecting CO₂ into these structures creates a synergistic storage mechanism for the trapping–mineralization–free phase, which can maximize the CO₂ storage potential within the stope volume. This potential can be estimated using the effective volume and mineral replacement methods. In summary, this study proposes CO₂ storage methodologies for abandoned metal mine goafs based on physical storage, mineral carbonation, and solubility-trapping technologies. The aim is to provide theoretical and technical underpinnings for the resource recovery of such spaces and to advance the strategic goals of carbon neutrality, both in China and globally.