New functional materials of metal chalcophosphates have been receiving increasing attention due to their wide structural diversity and technologically promising properties. In this work, a quaternary selenophosphate, Cs₂ZnP₂Se₆, has been successfully prepared by the high-temperature solid state reactions with a modified reactive CsCl flux. Single-crystal X-ray diffraction analyses show that Cs₂ZnP₂Se₆ crystallizes in triclinic space group P  with a = 7.66000(10), b = 7.712(7), c = 12.7599(3) Å, α = 96.911(18)°, β = 104.367(14)°, γ = 109.276(13)°, V = 672.16 ų and Z = 2. The major structure feature is the one-dimensional (1D) chain comprised of alternating units of tetrahedrally coordinated Zn²⁺ ions to the ethane-like [P₂Se₆]^4– units, in which counterbalanced Cs cations are accommodated. Significantly, photo-electrochemical measurement indicated that the title compound was photo-responsive under visible-light illumination. Moreover, the optical gap of 2.67 eV for Cs₂ZnP₂Se₆ was deduced from the UV/Vis reflectance spectroscopy and theoretical calculation shows an indirect band gap with an electronic transfer excitation of Se-4p to Zn-3d/4p and P-3p orbitals. This work presents not only a novel potential application of metal chalcophosphates, but also a facile approach to prepare alkali metal-containing chalcogenides.