Multimetal oxide with asymmetric atomic sites offers potential solutions for Fenton-like reactions, while their pilot-scale synthesis remains challenging. Herein, we develop a continuous flash Joule heating method using a programmable logic controller with robotic arms to accomplish proof-of-concept of scalable production. The pilot-scale product (178.3 kg·h⁻¹·m⁻² electrode) of fusion ternary metal oxides was achieved for flow-through water treatment. Integrating multiple reaction electrodes with respective independent power further outlined an increased production path. Experiments and density functional theory calculations proved that fusion CuVFeO structure achieved the dual functionality of organics adsorption on Cu sites and peroxydisulfate activation on Fe sites. The synergistic reaction can be strengthened by V doping endowed with a d band center, leading to an increased Fe Bader charge. Therefore, triple site effects shorten the reaction distance between free radicals (SO₄^•− and •OH) and organics, enhancing free radicals’ utilization and production efficiency. CuVFe secures superior performance during long-term operations (1455 min) in a continuous flow-through device. flash Joule heating characterization determined multi transition metals (CuVFe, CoVFe, MgVFe) can be generally synthesized with a superior catalytic performance. Undoubtedly, continuous flash Joule heating sheds light on developing advanced oxidation materials for pilot-scale wastewater treatment.