In this work, a novel NiO/Bi2O3/Bi3ClO4 heterojunction nanocomposite with high visible-light-driven photocatalytic performance has been fabricated via an improved Pechini sol-gel method. The results exhibited that by controlling the process parameters such as kind of carboxylic acids, gelling agents and molar ratio of carboxylic acid to metals, the NiO/Bi2O3/Bi3ClO4 nanocomposites with various morphologies were synthesized. Furthermore, compared to pure NiO/Bi2O3 and other nanocomposites, NiO/Bi2O3/Bi3ClO4 demonstrated more photodegradation efficiency with 89% removal of acid red 88 azo dye in 120 min under visible light irradiation after four times cycles. The enhanced photocatalytic performance can be attributed to the effective separation and transfer of the photoexcited electron-hole pairs, fine particle size distribution and favorable absorption capability of NiO/Bi2O3/Bi3ClO4 ternary nanocomposite. In addition, the reliable photocatalytic mechanism was explained on the basis of the radical trapping experiment, which revealed the photoinduced active species superoxide radicals and holes were the prevailing active species in the photocatalytic process.