Electrocatalytic conversion presents a promising alternative to conventional industrial catalysis. While aqueous-phase electrocatalysis has achieved notable advancements, oil–water immiscible systems remain challenging due to restricted reaction flux at multiphase interfaces. To address the limitation, we engineered a biphasic reaction system featuring a tailored oil–water catalytic interface in cyclohexene oxidation reaction (COR). The system employed a catalyst-loaded porous electrode as an active phase domain, enabling spatial separation of cyclohexene (organic phase) and electrolyte (aqueous phase). The tailored oil–water interface enhanced the interfacial mass transfer of substrate-catalysts and facilitated the spontaneous migration of 2-cyclohexen-1-ol into the aqueous phase, thereby streamlining product separation. Notably, polyaniline (PANI) modification on Co₃O₄ enhanced surface lipophilicity, promoting cyclohexene adsorption and accelerating the COR catalytic kinetics (Co³⁺–O + cyclohexene–H + e⁻ → Co²⁺–OH + 2-cyclohexen-1-ol). The synergistic effects of optimized interfacial engineering and catalyst functionalization achieved exceptional performance: a current density of 45 mA·cm⁻² at 1.6 V vs. reversible hydrogen electrode (V_RHE), coupled with 96.2% selectivity and 82.9% Faradaic efficiency. This work establishes an innovative paradigm for electrocatalytic conversions in oil–water immiscible systems through rational interface design and catalyst surface modulation.