The search for greener alternatives to perform organic reactions has become the order of the day in the chemistry community. In this regard, the use of heterogeneous photocatalysts has emerged as a powerful alternative to replace transition metal-based complexes and organic dyes to enable light-driven organic transformations. Within this realm, metal oxide semiconductors (MOS) have become increasingly popular due to their recyclability, availability, energy efficiency, photo- and chemical stability and generally low toxicity. Here, we cover the most relevant literature related to the use of MOS as photocatalysts to light induce organic reactions, including oxidations, C–C and C-heteroatom bond formations. We also discuss the mechanisms involved in these processes, as well as the hitherto best known MOS modifications able to enhance their photocatalytic performance.