Photoelectrocatalytic efficiency is mainly dependent on the light absorption of a photocatalyst electrode, charge separation and transport, and surface chemical reactions. To enhance photoelectrocatalytic efficiency, an ordered one-dimensional heterojunction photocatalyst consisting of Cu_xZn_1−xIn₂S₄ ultrathin nanosheets on electrochemically anodized TiO₂ nanotube arrays (CZIS@TNTAs) was successfully synthesized by a solvothermal reaction. It was found that the Cu_xZn_1−xIn₂S₄ ultrathin nanosheets on the TNTAs significantly enhanced visible light absorption and photoelectrochemical responses, and a near 8.0-fold increase in the photoelectrocatalytic hydrogen production rate was achieved compared to the blank TNTAs. Moreover, the CZIS@TNTAs exhibited excellent photoelectrocatalytic stability. Measurements of the flat-band and electrochemical impedance revealed the feasibility of charge transfer in the CZIS@TNTA hetero-systems, which was supported by PL and photoelectrochemical measurements. The superior photoelectrocatalytic activity of the CZIS@TNTA composite electrodes is mainly attributed to their enhanced light absorption and the separation of photo-generated charges, facilitating electron transport along the 1D TiO₂ structure.