Ovarian cancer (OC) remains one of the most challenging gynecologic malignancies due to its late-stage diagnosis, high recurrence rates, and limited survival outcomes. Immunotherapy has emerged as a transformative approach in cancer treatment, leveraging the immune system to target tumor cells. This chapter provides a comprehensive overview of immunotherapy in OC, discussing its mechanisms, key strategies, and clinical advancements. Key areas include the role of immune checkpoint inhibitors (ICIs), adoptive cell therapies (ACT), cancer vaccines, and oncolytic viruses. Despite promising preclinical and clinical outcomes, significant challenges persist, including low immunogenicity, resistance mechanisms, and immune-related adverse events. Strategies to address these barriers, such as combination therapies, biomarker-guided approaches, and the integration of artificial intelligence (AI) for personalization, are discussed. Emerging directions, including next-generation immune checkpoint targets and innovations in epigenetic and metabolic reprogramming, are explored to envision the future of immunotherapy in OC. By addressing these challenges and leveraging innovative strategies, immunotherapy has the potential to redefine the therapeutic landscape, improving survival and quality of life for patients with OC.