Abstract: When electrokinetic remediation (EKR) is applied to treat arsenic (As)-contaminated soil from acid mine drainage, its remediation efficiency is constrained by the strong adsorption of As by iron oxides. To overcome this limitation, this study added two reagents, sodium thiosulfate and fulvic acid (FA), to the soil to promote As migration and enhance remediation performance. The results showed that adding sodium thiosulfate increased soil moisture content, electrical conductivity, and electroosmotic flow rate, and strengthened the soil reducing environment, thereby facilitating the reductive dissolution of iron oxides and the activation of As. The combined use of sodium thiosulfate and fulvic acid effectively inhibited the formation of secondary iron minerals, weakened the re-adsorption of As, and further improved As removal efficiency. This combined strategy could maintain As mobility over a long period and significantly enhance electrical energy utilization efficiency in the later stage of remediation (8-14 days), and the energy consumption per unit mass of As removed (corresponding to a 1% increase in removal rate) in the later stage was only about 36.2% of that in the early stage (1-7 days). After 14 days of EKR treatment, the As removal rate in the combined group of sodium thiosulfate and fulvic acid increased from 5.51% (in the reagent-free group) to 35.32%. The As removal in this study was mainly attributed to the reduction of iron oxides and the transformation of residual As. In addition, the sole addition of sodium thiosulfate reduced the removal rates of coexisting heavy metals (Pb, Sb, and Cu) in the soil by EKR; however, the combined use of the two reagents could simultaneously enhance the remediation efficiency for Pb and Cu. The findings confirm that the combined enhancement strategy of sodium thiosulfate and fulvic acid exhibits considerable application potential in the remediation of As-contaminated soil using EKR. This strategy not only provides new insights into the synergistic remediation of heavy metal complex-contaminated soil but also offers reference for further optimization and engineering application of EKR technology.