Extracellular polymeric substances (EPS), as a key component of soil organic carbon (SOC) sequestration, have long been overlooked. Although the prevalent theories emphasize microbial cell residues as the dominant contributor to SOC formation, emerging evidence indicates that EPS is widely present in soils and is produced at rates comparable to or even higher than cellular biomass, representing a major pathway of microbially derived carbon input into soils. This review systematically synthesizes current knowledge, with a focus on the distinctive role of EPS in soil carbon stabilization. We summarized four key mechanisms through which EPS promote soil organic carbon stability: the formation of mineral-associated organic matter, participation in geopolymerization reactions, driving the formation of soil aggregates, and regulating pore structure. This reveals the pathway for achieving carbon sequestration through both direct and indirect effects. Following our findings, we outline future research priorities, emphasizing the need to develop reliable extraction and quantification methods, incorporate EPS dynamics into SOC models, and elucidate the environmental and microbial factors regulating EPS production and degradation. Addressing these gaps will significantly advance our understanding of microbial roles in the global carbon cycle and inform strategies for enhancing soil carbon sequestration.