The preparation of multifunctional hybrid semiconductor nanomaterials could be a good approach to increase the visible light absorption, electron-hole (e−/h+) pair separation rate and photocatalytic degradation of the organic pollutants. Herein, an efficient ternary heterojunction photocatalyst (TiO2/GO/g-C3N4) was synthesized from the mixtures of the graphene oxide (GO) nanosheets, TiO2 nanoparticles, and graphitic carbon nitride (g-C3N4) by simple mechanical stirring followed via calcination procedure. The performance of prepared photocatalyst for degradation of malachite green (MG) under UV light irradiation was investigated. The PL spectrum showed the rapid separation of the e−/h+ pair, and reduction in the bandgap energy of the TiO2/GO/g-C3N4 nanocomposite. The porous-layered structure of graphene oxide and graphitic carbon nitride promotes superior dispersion of TiO2 nanoparticles and consequently enhances absorption sites and photocatalytic reaction sites. Furthermore, the graphitic carbon nitride expands light absorption range and increases the light harvest. Meanwhile, graphene oxide accelerates the photogenerated carrier separation and effectively quenches charge recombination in the photocatalyst because of the high conductivity. The active species trapping indicate that the important forms in MG degradation are •O2–, •OH, and h+. The reusability investigation of the spent catalyst showed the 95% degradation of MG after four consecutive cycles imply that TiO2/GO/g-C3N4 nanocomposite is a stable and efficient catalyst. The high efficiency and reusability of the TiO2/GO/g-C3N4 nanocomposite could be related to the excellent light absorption and sensitizing effect of the graphene oxide and graphitic carbon nitride.