In the present study, CuBi2O4/Bi3ClO4 nanocomposites have been fabricated via an improved Pechini sol-gel process using the mixtures of various gelling agents and polybasic acids. This work shows that by controlling the reaction conditions such as kind of polybasic acids, gelling agents, pH and mole ratio of polybasic acid to total metals, the CuBi2O4/Bi3ClO4 nanocomposites with ultrafine sphere-like, irregular polyhedral-like, plate-like and cubic-like morphologies were prepared. The phase, elemental composition, morphology and optical characteristics of as-synthesized CuBi2O4/Bi3ClO4 nanostructures were analyzed utilizing UV-Vis, FESEM, TEM, HRTEM, FT-IR, XRD, TOC and EDS techniques. Furthermore, the CuBi2O4/Bi3ClO4 nanocomposites exhibited excellent TOC removal (75%) and photocatalytic activity (92%) to photodegradation of acid brown 14 azo dye as water pollutants under visible light irradiation. The excellent degradation activity of CuBi2O4/Bi3ClO4 photocatalyst can be attributed to the strong visible light absorption, high charge separation efficiency, fine particle size distribution and proper band gap of the nanocomposite. In addition, the reliable photocatalytic mechanism was discussed on the basis of the radical trapping study, which revealed the h(+) and O-2(-) radicals were the prevailing active species in the photocatalytic process.