Multiband materials have received increasing attention due to their superior solar absorption properties. Here we design a new multiband compound, namely Ba₅Bi₂Co₂S₁₀, which crystallizes in the space group C²_2h-P2₁/m (No. 11) of the monoclinic system. Ba₅Bi₂Co₂S₁₀ is composed of one-dimensional ¹_∞[Bi₂Co₂S₁₀]¹⁰⁻ chains along the a axis. The adjacent chains are separated by Ba²⁺ ions. The optical band gap of the compound is 1.05 eV and 0.74 eV, presenting typical multi-absorption characteristics. First-principles calculations, which are perfectly consistent with the experimental results, show that the hybrid coupling effect between Co and S gives rise to multiband characteristics. Evident optoelectronic conversion properties were observed under visible light illumination with a photocurrent density of 4.0 mA cm⁻² at 1 V.