The power generation capacity of the microbial fuel cell (MFC) depends largely on the properties of the cathode material. The key to achieving remarkable performance of MFC is to have good oxygen reduction reaction (ORR) activity. In this research, a novel, facile, and low-cost method involving surfactant-less stirring and ultrasound steps was used to prepare the catalyst. The silver vanadate blended functionalized multiwall carbon nanotubes (AgVO3@f-MWCNTs) illustrated a high ORR activity with a maximum power density of 106.8 mW m−2, which was about 3.73, and 2.84 times higher than that of AgVO3 (28.62 mW m−2) and f-MWCNTs (37.55 mW m−2), respectively. The f-MWCNTs provide a large specific surface area that can increase the loading and dispersion of active sites, together with the synergistic catalysis of AgVO3 active sites, greatly improving the ORR performance of the MFC. Furthermore, the AgVO3@f-MWCNTs cathode catalyst demonstrated that the composite materials had great potential for new green energy strategies.