With Rhodamine B as a model compound, the photocatalytic oxidation of organic contaminants in aqueous solution was investigated within a cooperating porous BiVO4/H2O2 system under simulated sunlight irradiation. Peanut-shaped porous BiVO4 was prepared through a simple template-free solvothermal method with high yield, and was used in the cooperating catalyst/H2O2 system. The possible formation mechanism of peanut-shaped BiVO4 nanostructures was investigated. In the peanut-shaped BiVO4/H2O2 system, nearly complete degradation of Rhodamine B was observed after 60 min of irradiation under sunlight irradiation. The as-obtained porous BiVO4 photocatalyst displayed higher photocatalytic activity than those of the reference product hydrothermally synthesized and the photocatalyst P25 in the same catalyst/H2O2/sunlight system. The photocatalytic processes of the BiVO4/H2O2/sunlight system may consist of both OH˙ oxidation and direct hole attack. In addition, the peanut-shaped porous BiVO4 nanostructures were stable and maintained high photocatalytic efficiency during repeated recycles in the H2O2-containing system.