Triboelectric-electromagnetic hybrid generator (TEHG) has emerged as an effective technology for mechanical energy harvesting. However, the independent operation of triboelectric nanogenerator (TENG) and electromagnetic generator (EMG), along with tribo-materials wear and magnetic field divergence, constrain the device's overall performance. To address these challenges, a synergistically enhanced TEHG (SE-TEHG) is proposed based on the multifunctional amorphous alloy. Following detailed material analyses, Fe72Si8B20 is selected as the synergistic layer for its low surface roughness, high Vickers-hardness, amorphous structure, and high magnetization. Compared to Al, this material not only boosts TENG's output current and current retention rate by 28.75% and 85.24%, but also improves EMG's output power by 51.05%. In constructing a self-powered system with TEHG, a significant impedance discrepancy exists between the energy harvester (with matched impendence of 16 MΩ for TENG and 110 kΩ for EMG) and the application end. Without power management circuits, the demonstrated self-powered variable impedance system achieves an energy utilization efficiency that is 2.98 times greater than the conventional constant impedance system. The integration of multifunctional materials to realize strong-coupling hybrid generators, combined with the customization of variable impedance systems, set a milestone in efficient mechanical energy harvesting and utilization.