TiO₂ is a semiconductor material with high chemical stability and low toxicity. It is widely used in the fields of catalysis, sensing, hydrogen production, optics and optoelectronics. However, TiO₂ photocatalyst is sensitive to ultraviolet (UV) light; this is why its photocatalytic activity and quantum efficiency are reduced. To enhance the photocatalytic efficiency in the visible light range as well as to increase the number of the active sites on the crystal surface or inhibit the recombination rate of photogenerated electron–hole pairs electrons, various metal ions were used to modify TiO₂. This review paper comprehensively summarizes the latest progress on the modification of TiO₂ photocatalyst by a variety of metal ions. Lastly, the future prospects of the modification of TiO₂ as a photocatalyst are proposed.