Semiconductor photocatalysts are efficient degraders of organic and inorganic waste water pollutants. Herein, we synthesized nickel–titanium dioxide (Ni–TiO2) nanoflakes using Mukia maderaspatana leafs with the aim of analyzing their photocatalytic degradation potential. Morphological analyses revealed that the nanoflakes were highly agglomerated with an average size of 100 nm. Further, elemental analysis confirmed the presence of Ti, O, and Ni, whereas Fourier transform infrared spectroscopy and X-ray diffraction established the presence of TiO2 and NiO. We found that photocatalytic degradation of congo red under UV illumination increased with increasing incubation period, demonstrating that Ni–TiO2 nanoflakes can be used as optimal photocatalysts for the degradation of dyes in waste water.