Organic silver-rich selenidostannate hybrid [H3dien][Ag5Sn4Se12]∙3H2O (1) was prepared in diethylenetriamine (dien) solvent under solvothermal conditions. In 1, the triangular AgSe3 and tetrahedral AgSe4 units are linked through corner-sharing to form a 1-D [Ag5Se8]n chain. Two SnSe4 tetrahedra are joined by sharing common edge forming a Sn2Se6 dimeric unit. Acting as a tetradentate linker, the Sn2Se6 unit connects the [Ag5Se8]n chains into polymeric 3-D [Ag5Sn4Se12]n3n− anionic framework, which contains 1-D channel with sectional dimensions of 7.339 Å × 8.575 Å. The dien and H2O molecules are enclosed in the channels. Compound 1 shows semiconducting properties with narrow band gap of 1.82 eV and strong photocurrent response with steady photocurrent intensity of 109 μA under Xe light irradiation. Compound 1 exhibits excellent photocatalytic effective in the photodegradation of MB under visible light irradiation at room temperature.