Here, we report that layered metallic vanadium diboride (VB₂) can function as an active cocatalyst for efficiently catalyzing photocatalytic hydrogen evolution in a dye-sensitized system under visible light irradiation. In an Erythrosin B–triethanolamine (ErB–TEOA) molecular system, the highest turnover number (TON) of hydrogen evolution based on ErB reaches 40. In addition, VB₂ outperforms V₂O₅, VS₂, VN, and VC for photocatalytic hydrogen evolution.