One-dimensional ternary nanostructures, Ag2CO3 nanorod cores coated with an intermediate layer of Ag nanoparticles (NPs) and a sheath of conducting polymer polyaniline (PANI), Ag2CO3/Ag/PANI composite nanorods (CNRs), were successfully prepared via a facile two-step method. Ag NPs were first uniformly anchored onto the Ag2CO3 nanorods to form binary Ag2CO3/Ag CNRs with an in situ visible-light-induced reduction strategy, and then the Ag2CO3/Ag CNRs were coated with PANI of different contents through a simple chemisorption approach. The as-obtained hybrids exhibit significantly enhanced photoelectrochemical current response and photoactivity in degrading methyl orange under visible-light illumination (lambda > 420 nm). The improved photoactivity was found to be related to the intermediate Ag between Ag2CO3 and PANI which facilitates the separation efficiency of photogenerated carriers, and an optimal weight percent of 2.0% PANI was observed. The origin of enhanced photoactivity was further investigated by a radical-trapping test, and a Z-scheme mechanism was proposed to explain the charge separation behaviors.