Microbial sulfur oxidation coupled with arsenate reduction (SOAsR) is a key biogeochemical process in oligotrophic mining-impacted habitats, particularly in mine tailings. This study investigated the prevalence and mechanisms of SOAsR in mine tailings from southern China. Geochemical analysis and molecular techniques revealed that SOAsR is more prevalent than heterotrophic arsenate reduction in these environments. The water-soluble reduced sulfur concentration was identified as a major geochemical parameter influencing SOAsR potential. DNA stable isotope probing and metagenome binning identified members of the genera Sulfuricella, Ramlibacter, and Sulfuritalea as sulfur-oxidizing arsenate-reducing bacteria (SOAsRB). Genome mining expanded the list of potential SOAsRB to diverse phylogenetic lineages, including those associated with Burkholderiaceae and Rhodocyclaceae. Metagenomic analysis confirmed that putative SOAsRB were dominant arsenate reducers in these sites. The study highlights the importance of SOAsR in biogeochemical arsenic cycling in mine tailings and suggests its potential for future remediation strategies. Key findings include the role of reduced sulfur species as primary electron donors in SOAsR, the phylogenetic diversity of SOAsRB, and their significant contribution to arsenate reduction in mine tailings. The results emphasize the need to consider microbial sulfur oxidation in the remediation of arsenic-contaminated environments.Microbial sulfur oxidation coupled with arsenate reduction (SOAsR) is a key biogeochemical process in oligotrophic mining-impacted habitats, particularly in mine tailings. This study investigated the prevalence and mechanisms of SOAsR in mine tailings from southern China. Geochemical analysis and molecular techniques revealed that SOAsR is more prevalent than heterotrophic arsenate reduction in these environments. The water-soluble reduced sulfur concentration was identified as a major geochemical parameter influencing SOAsR potential. DNA stable isotope probing and metagenome binning identified members of the genera Sulfuricella, Ramlibacter, and Sulfuritalea as sulfur-oxidizing arsenate-reducing bacteria (SOAsRB). Genome mining expanded the list of potential SOAsRB to diverse phylogenetic lineages, including those associated with Burkholderiaceae and Rhodocyclaceae. Metagenomic analysis confirmed that putative SOAsRB were dominant arsenate reducers in these sites. The study highlights the importance of SOAsR in biogeochemical arsenic cycling in mine tailings and suggests its potential for future remediation strategies. Key findings include the role of reduced sulfur species as primary electron donors in SOAsR, the phylogenetic diversity of SOAsRB, and their significant contribution to arsenate reduction in mine tailings. The results emphasize the need to consider microbial sulfur oxidation in the remediation of arsenic-contaminated environments.