Bimetallic electrocatalysts can leverage synergistic effects to efficiently catalyze the degradation of neonicotinoid pesticides, but their application is constrained by diminished active sites due to the aggregation of metal nanoparticles. By anchoring metallic species onto nanofibers through electrospinning and achieving in-situ integration of metal oxides with carbon fibers via thermal treatment, we successfully constructed an iron-manganese bimetallic electrocatalyst (FM@N-CNF), featuring uniformly dispersed metal oxides with an average particle size of 6 nm. Electrochemical characterization confirmed that FM@N-CNF exhibits superior electrochemical active surface area and electron transfer capability compared to monometallic catalysts. When employed as a cathode material at -0.5 V vs. SCE, FM@N-CNF achieved complete degradation of thiamethoxam within 90 minutes and maintained degradation rates above 80% over 10 consecutive cycles. The catalyst demonstrated excellent environmental adaptability under various conditions, including pollutant concentrations (5 ~ 100 ppm), pH (3 ~ 11), and coexistence of common inorganic salts. Quenching experiments in combination with electron paramagnetic resonance (EPR) spectroscopy consistently identified singlet oxygen (1O?) as the predominant reactive oxygen species. Liquid chromatography-mass spectrometry analysis revealed that the degradation pathway of thiamethoxam primarily involves carboxylation and carbonyl addition reactions.