As an important biological secretion, the potential role of earthworm epidermal mucus in regulating soil carbon cycling has not been fully understood. Based on a 14-year long-term field experiment in red soil, this study systematically analyzed the metabolic composition and ecological function of epidermal mucus from two ecological types of earthworms (epigeic earthworms and endogeic earthworms), and explored its impact on the expression of soil carbon-metabolizing enzymes and functional gene composition through metagenomics and mucus addition experiments. The results showed that: 1) The types of metabolites in the mucus of the two earthworm types were largely similar, but their relative abundances significantly differed. Epigeic earthworm mucus was rich in organic acid and its derivaties, lipids, and heterocyclic compounds, while endogeic mucus contained a higher proportion of organic acid and its derivaties. Pathway enrichment analysis revealed distinct enrichment patterns in secondary metabolite biosynthesis pathways between the two types. 2) According to the metagenomic analysis, earthworm addition significantly increased the abundance of key enzymes such as pyruvate kinase, malate synthase, and phosphoserine aminotransferase, with some enzymes showing more than an 8% increase in expression. 3) The earthworm mucus enriched in amino acids and plant secondary metabolites, and enhanced the activities of β-glucosidase and polyphenol oxidase, thereby improving the accumulation and transformation of soil organic carbon. These findings suggest that earthworm epidermal mucus can mediate biochemical interactions between earthworms and soil by regulating the expression of key carbon-metabolizing enzymes, providing new theoretical insights into the role of earthworms in biological soil improvement and carbon sequestration in red soils.