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Imidacloprid (IMI), as the most-consumed pesticide, has posed a severe threat to the water ecosystem due to its recalcitrance and inefficient elimination in the traditional wastewater treatment. Herein, a heterogeneous electro–Fenton (EF) system coupled with 3D–MoO 2 –porous biochar (PBC) cocatalytic electrodes, abbreviated as 3D–MPE–EF, is initially applied to promote the elimination of IMI in the agrochemical wastewater from pesticide production. The elimination rate of IMI by 3D–MPE–EF system is 18.15 times higher than that by traditional EF system at pH 7.0. The utilization of 3D–MoO 2 –PBC electrodes sufficiently compensates for inherent deficiencies of traditional EF system. The circular utilization of Fe is also addressed by 3D–MoO 2 –PBC cocatalytic electrodes to reduce the consumption of Fe2+ and the deposition of iron mud. Through comparison, MoO 2 is considered the most appropriate cocatalyst in terms of the reutilization of Fe and degradation of IMI. Eight mechanisms are identified in the degradation pathways of IMI by UPLC–Q–TOF–MS. The ecotoxicities of IMI are remarkably attenuated in the 3D–MPE–EF system. This study provides insights into the roles of 3D–MoO 2 –PBC cocatalytic electrodes in the enhanced elimination of IMI in heterogeneous EF system. [Display omitted] • The IMI removal by EF system is greatly enhanced by 3D–MoO 2 –PBC electrodes. • The alkaline elimination of IMI is promoted by 3D–MoO 2 –PBC electrodes. • The reutilization of Fe is addressed by MoO 2 to reduce the deposition of iron mud. • Eight plausible degradation mechanisms of IMI were identified in 3D–MPE–EF. • The ecotoxicity of IMI were progressively attenuated in the 3D–MPE–EF system. [ABSTRACT FROM AUTHOR]