The present study reports a novel, simple, economic and ecofriendly method to synthesize Titanium dioxide (TiO2) nanoparticles using green alga Chlorella pyrenoidosa. Further, these TiO2 nanoparticles were deposited on GO sheets to form TiO2-GO nanocomposite. The crystalline information, morphological and optical properties of the synthesized TiO2-GO nanocomposite were studied using X-ray Diffraction (XRD), Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy (SEM-EDX) and UV Vis absorption spectroscopy. Crystal Violet (CV) dye was used as a model contaminant. The photocatalytic activity of TiO2 nanoparticles and the TiO2-GO nanocomposite were evaluated by the degradation of CV dye in aqueous medium under visible light. The result showed that the TiO2-GO nanocomposite exhibited higher photocatalytic efficiency compared to pristine TiO2 nanoparticles with three cycles reusability. The improved activity of the TiO2-GO nanocomposite might be attributed to enhanced charge separation, efficient charge transportation, extended light absorption range and increased adsorption of dye. This nanocomposite has a great potential in removing environmental contaminants and applicable in water purification.