Introducing anion and cation vacancies into Co-based oxides is a promising strategy to promote their catalytic activity. However, the mild and effective methods for synthesizing cobalt oxide and vacancies are rarely proposed. In this work, via an innovative one-step hydrothermal process, we synthesized Co3O4-based catalyst, which was successively proven rich with oxygen vacancies (V-O) and cobalt vacancies (V-Co). As an electrocatalyst for benzyl alcohol (BA) oxidation, the vacancy-rich Co3O4 on nickel foam (NF) with optimized electronic structure displayed a super high conversion (> 99%) and selectivity (> 99%) for benzoic acid (BAc) with excellent recyclability, representing one of the best Co-based catalysts. X-ray photoelectron spectroscopy (XPS) and X-ray adsorption near-edge structure (XANES) technologies coupled with density functional theory calculations (DFT) demonstrated the obvious electronic delocalization caused by vacancies not only lowered the adsorption energy of BA and improved the intrinsic activity of catalytic Co sites for faster reaction kinetics, but also narrowed the band gap for better electrical conductivity. This work opens up a new simple synthetic idea to construct the high-performance electrocatalysts by tuning electronic structure.