Widespread application of Li‐ion batteries (LIBs) in large‐scale transportation and grid storage systems requires highly stable and safe performance of the batteries in prolonged and diverse service conditions. Oxygen release from oxygen‐containing positive electrode materials is one of the major structural degradations resulting in rapid capacity/voltage fading of the battery and triggering the parasitic thermal runaway events. Herein, the authors summarize the recent progress in understanding the mechanisms of the oxygen release phenomena and correlative structural degradations observed in four major groups of cathode materials: layered, spinel, olivine, and Li‐rich cathodes. In addition, the engineering and materials design approaches that improve the structural integrity of the cathode materials and minimize the detrimental O2 evolution reaction are summarized. The authors believe that this review can guide researchers on developing mitigation strategies for the design of next‐generation oxygen‐containing cathode materials where the oxygen release is no longer a major degradation issue. The oxygen release from cathodes in the presence of organic electrolyte decomposition products can trigger thermal runaway reactions and battery failure. Overcharging the cathodes, high temperatures, high voltage cycling, or abusing electrochemical cycling can facilitate the reactions leading to oxygen release from cathodes. This article reviews the mechanisms underlying the oxygen release phenomenon and mitigation strategies to prevent it.