Abstract: With accelerating industrialization, soil heavy metal pollution has become an increasingly severe issue. Chromium (Cr) contamination primarily originates from industrial discharges, such as leather processing, textile printing, and dyeing, as well as agricultural activities. Chromium predominantly exists in trivalent and hexavalent forms. Compared to Cr(III), which exhibits low mobility and readily adsorbs onto soil particles, hexavalent chromium Cr(VI) exhibits high toxicity and mobility. It readily disperses via groundwater, posing a severe threat to ecological safety. Although electrokinetic (EK) remediation holds great potential for treating low-permeability soils due to its unique electrically driven mechanism, this technology is often constrained by the "focusing effect." This phenomenon involves the accumulation of pollutants at electrode interfaces during migration, resulting in limited removal efficiency and uneven distribution. To overcome this bottleneck, this study designed an electrokinetic-permeable reactive barrier (EK-PRB) system to achieve in situ interception and removal of pollutants by incorporating a modified activated carbon PRB layer. The study systematically investigated the synergistic mechanisms between the electrolyte and PRB materials. Specifically, activated carbon was functionalized using hydrochloric acid and cetyltrimethylammonium bromide (CTAB, a cationic surfactant), respectively, to regulate the pore structure and surface charge. Three electrolytes with distinct driving mechanisms—citric acid, potassium chloride, and sodium dodecylbenzenesulfonate (SDS)—were introduced. Remediation efficacy was evaluated by monitoring current, pH distribution, and the spatiotemporal migration of chromium. The results indicated that remediation efficiency depended on the compatibility between the electrolyte and the PRB material. The combination of citric acid (CA) electrolyte with hydrochloric acid-modified activated carbon demonstrated optimal performance, achieving removal rates of 93.1% for Cr(VI) and 77.95% for total chromium. This performance is attributed to the strong chelating action of citric acid, which effectively promoted the desorption and migration of adsorbed chromium, while the acid-modified PRB layer provided abundant active sites for the precise interception of chromium ions. Comparative analysis confirmed that the anolyte chromium concentration in the EK-PRB group was significantly lower than that in the conventional EK group, demonstrating the PRB layer's efficacy in mitigating anode enrichment. Furthermore, BCR speciation analysis revealed that this technology substantially altered the chemical speciation of chromium. Post-remediation, the soil exhibited reductions exceeding 91.2% and 64.12% in bioavailable weak acid extractable and reducible chromium, respectively—the most environmentally hazardous forms. In summary, compared to conventional EK remediation, the EK-PRB technology not only achieves high-efficiency remediation but also promotes uniform removal and deep stabilization of chromium by significantly reducing high-risk fractions.