Reversible deactivation radical polymerization (RDRP) is a class of powerful techniques capable of synthesizing polymers with a well‐defined structure, properties, and functionalities. Among the available RDRPs, ATRP is the most investigated. However, the necessity of a metal catalyst represents a drawback and limits its use for some applications. O‐ATRP emerged as an alternative to traditional ATRP that uses organic compounds that catalyze polymerization under light irradiation instead of metal. The friendly nature and the robustness of O‐ATRP allow its use in the synthesis of tailorable advanced materials with unique properties. In this review, the fundamental aspects of the reductive and oxidative quenching mechanism of O‐ATRP are provided, as well as insights into each component and its role in the reaction. Besides, the breakthrough recent studies that applied O‐ATRP for the synthesis of functional materials are presented, which illustrate the significant potential and impact of this technique across diverse fields.