Nanoparticles (NPs) of titanium dioxide (TiO₂) have attracted a lot of attention as a potential photocatalyst for the degradation of pollutants, especially synthetic dyes like methyl orange, rhodamine B, and methylene blue (MB). Understanding the applicability of TiO2 nanoparticles in MB degradation requires emphasizing their unique physicochemical qualities, such as their large surface area, substantial oxidative potential, and outstanding chemical stability. The formation of reactive oxygen species (ROS) via photoinduced synthesis of electron–hole pairs under ultraviolet (UV) light irradiation is the central focus of a thorough investigation of the photocatalytic process of TiO₂. Through redox processes started by these electron–hole pairs exposed to solar light, TiO₂ aids in the breakdown of MB into less harmful byproducts in wastewater treatment. The important variables influencing photocatalytic performance are particle size, crystal phase (anatase, rutile, and brookite), surface modifications, and the addition of metal or non-metal dopants to enhance visible light absorption. The electron–hole pair separation make TiO₂ NPs feasible for photocatalysis, and this is possible for their large band gap, which was not in their bulk form. In the nano form, they have the same number of electrons as their bulk form but a large band gap at the semiconductor level. The main objective of this study is to fill knowledge gaps on TiO₂-based photocatalysis for MB degradation and suggest improvements to make these systems better for future wastewater treatment that is both efficient and sustainable.