This chapter focuses on the advancements in the highly significant field of photocatalytic degradation of dyes by the metal oxide nanomaterials. These dyes exist as key pollutants in industrial wastewater, which adversely impact the serenity of ecosystem. For the degradation of such harmful organic dyes, photocatalysis is a simple, effective, and inexpensive route. In photocatalysis, the catalysts adsorb water contaminants on their surface, initiating charge mobility that advances the redox capability of the catalysts. In recent decades, semiconducting metal oxide nanomaterials and nanocomposites have been investigated significantly as photocatalysts for the efficient degradation of organic dyes. Metal oxides have complex configurations and significant physical characteristics, such as differences in oxidation states, symmetry, coordination numbers, density, and surface features, etc., in comparison to the other materials. In this perspective, photocatalytic applications of metal oxides, like TiO2, ZnO, SnO2, NiO, and MgO and their various nanocomposites have been reviewed and emphasized alongwith the advancements in various dye degradation by these metal oxides.