Two new chromium and manganese bimetallic nanoclusters, [Cr_8−xMn_x(OH)_8−x(H₂O)_x(OOCC₆H₅)₁₆, x = 1.11] (1) and [Cr₄Mn₄O₄(OOCC₆H₅)₁₂·3CH₃CN·H₂O] (2), have been synthesized in a one-pot solvothermal reaction in this work. Under visible irradiation, cluster 1 can produce an increased photocurrent and exhibits significant visible-light-driven photocatalytic activity for H₂ evolution in an aqueous system. Most importantly, it exhibits ultrahigh stability in both acid and base aqueous solutions, making it an excellent synthon for preparing functional materials.