The current paper outlines the synthesis of pristine multi-wall carbon nanotubes (PMWCNTs)/Vanadium pentoxide V2O5 and functionalized multi-wall carbon nanotubes (FMWCNTs)/V2O5 nanocomposite for photocatalytic applications. The FMWCNTs were obtained by the oxidizing agents (H2SO4 and HNO3) to introduce the oxygenated functional groups. The samples were synthesized by hydrothermal approach and investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy analysis (EDX), and Fourier transform infrared spectroscopy (FTIR). The photocatalytic activity of multi-wall carbon nanotubes (MWCNTs), FMWCNTs/V2O5, and PMWCNTs/V2O5 nanocomposites was assessed via methylene blue (MB) degradation from water under visible light. The results demonstrated that the removal efficiency of MB by PMWCNTs, FMWCNTs/V2O5, and PMWCNTs/V2O5 could reach 90.4, 98.9, and 94.9%, respectively. It was noticed that MB adsorption and photodegradation tend to follow pseudo-second-order kinetics. The mechanism of MB photodegradation by FMWCNTs/V2O5 nanoparticles was explained. MWCNTs/V2O5 nanocomposites will allow further applications to remove other dyes and contaminants from wastewater.