A novel bimetal seleno-sulfide (Cu,Mn)(Se,S) nanosheet catalyst was synthesized by a hydrolysis route in water solvent. The results indicated that the multi-component (Cu,Mn)(Se,S) solid solution-type catalyst prepared without N2H4 displayed excellent oxidation/degradation activities over methylene blue, nitrobenzene, and pchlorophenol even in the dark. The (Cu,Mn)(Se,S) prepared with 0.30 ml N2H4 displayed excellent reduction activities over Cr(VI), Pb(II), and Hg(II) even in the dark. The recycling of toxic heavy metals becomes feasible in the dark. The (Cu,Mn)(Se,S) catalyst also performed well for the reusability tests. The excellent performance can be attributed to vacancies at the anion sites to interact with reactants and the charge hopping between the Cu+ and Cu2+ cations. The (Cu,Mn)(Se,S) catalyst with the excellent redox activity without the light illumination can broaden the practical application of photocatalyst.