Currently, more and more attention is being paid to the use of local and systemic methods of ozone therapy. Ozone has a wide range of medicinal properties, including antioxidant, antihypoxant, bactericidal, anti-inflammatory, immunomodulatory, and analgesic effects. Due to these properties, ozone therapy is becoming increasingly popular in the treatment of acute surgical pathology, especially in patients with peritonitis. It is important to note that with widespread purulent peritonitis, systemic cellular hypoxia plays a key role, which leads to energy deficiency and the formation of free radicals in various organs and systems of the body. This paper presents modern data on the main mechanisms of action and biological effects of the use of medical ozone for the treatment of widespread peritonitis. Specific methods of ozone therapy and their effectiveness, confirmed both by experimental studies on animals and by the results of clinical practice, are considered. Ozone therapy is a promising method in the complex treatment of patients with widespread peritonitis. Its use can reduce inflammation, improve tissue oxygenation, activate metabolic processes, and restore energy balance in the body. This opens up new opportunities for effective treatment and rehabilitation of patients with peritonitis.