By integrating Lewis Acid-base and Internal Electro Field (IEF) into the design of a composite electrode material that does not rely on precious metals, this research aims to improve the detection of unsymmetrical dimethylhydrazine (UDMH), a hazardous environmental pollutant. This innovative approach addresses high costs and low sensitivity, enhancing detection in environmental monitoring and remediation. The hydrogen bond generated by Lewis Acid–Base and the IEF interactions produced by the bridging oxygen atoms on Bi surfaces interact synergistically to enhance the physical and chemical adsorption of UDMH, leading to its oxidation to CH3N=CH2. The method involves growing vertically aligned bismuth nanoflower electrodes (Bi NFs) on the carboxylated monolayer graphene oxide (MGO-COOH) surface, significantly enhancing UDMH detection sensitivity by 10.7 times within a range of 0.1 to 1 μg∙L−1, with a low detection limit of 0.525 μg∙L−1 and excellent recovery rates ranging from 94% to 108%. The electrodetection and electrooxidation mechanism of UDMH molecules by Bi NFs/MGO-COOH/GCE were further explored with density functional theory (DFT) and Fourier-transform infrared spectroscopy (FT-IR). This work demonstrates the cost-effective, highly sensitive detection of UDMH using Lewis Acid-Base and IEF surface interactions.