Hexavalent chromium (Cr(VI)), characterized by its potent oxidative activity and high aqueous mobility, is commonly found in industrial effluents and presents significant risks to both environmental and human health. Cr(VI) can inhibit plant growth, harm aquatic organisms, and cause genetic mutations and cancer. Therefore, the development of efficient remediation technologies is of critical importance. Microbial remediation has become a focal area of research for Cr(VI) removal, owing to its cost-effectiveness, high efficiency, and eco-friendly nature. This study isolated an endophytic Bacillus cereus strain Q-0 from the rhizosphere of grass roots grown in chromium contaminated soil. Unlike previously reported microorganisms for repairing hexavalent chromium, Bacillus cereus Q-0 exhibited excellent tolerance to high concentrations of hexavalent chromium (up to 1200 mg/L), can completely remove 100 mg/L hexavalent chromium after 60 h under optimal conditions of 35 °C, pH 8, and 180 rpm. Further studies revealed that B. cereus Q-0 removes Cr(VI) through four main pathways: (1) adsorption, complexation, and reduction reactions mediated by functional groups on the cell surface; (2) ion transport via membrane channel proteins; (3) enzymatic reduction facilitated by intracellular and membrane-associated reductases; and (4) promotion of Cr(VI) reduction using substrates in the medium as electron donors. These findings provide both microbial resources and a theoretical basis for the bioremediation of Cr(VI)-contaminated soils.