Remediation of former wood treatment sites is challenging due to the presence of contaminants with distinct physicochemical properties, such as arsenic (As) and polycyclic aromatic hydrocarbons (PAHs). This study evaluated a low-voltage electricity-induced soil remediation method designed to immobilize As while simultaneously degrading PAH in situ. A field pilot experiment was conducted at a highly contaminated site using iron (Fe) electrodes supplying pulsed direct current to promote PAH oxidation and Fe release from electrodes for As immobilization. Groundwater in five wells was monitored for concentrations of contaminants, their degradation byproducts, and microbial and fungal community structures. Over two years, dissolved PAH16 concentrations decreased by 62–94% across wells, with no accumulation of oxygenated or nitrogen-containing PAH. Dissolved As concentrations declined by up to 88% at low PAH levels, but reductions were weaker (55–57%) and more variable at very high PAH concentrations (hundreds to thousands μg L–1). Microbial communities, both prokaryotic and fungal, were characterized by taxa often found in contaminated aquifers and soils, with enrichment of PAH-degrading and As-tolerant Pseudomonas, Rugosibacter, and Duganella, but showed no adverse effect of the treatment. Overall, the method promoted concurrent PAH degradation and As immobilization with minimal secondary impacts, demonstrating potential for remediation of mixed-pollutant soils.