Except for its use in palliative care, radiotherapy has been largely abandoned in the management of ovarian cancer because of the recognised efficacy and lower toxicity of systemic chemotherapy compared with radiotherapy. New data have emerged that show synergy of radiotherapy with immunotherapy to control or eradicate cancer. Different doses of hypofractionated radiotherapy have been shown to induce immunogenic cell death and in-situ vaccination in several tumour models. However, doses less than 2 Gy can also reprogramme the tumour microenvironment. This Series paper discusses the past and present use of radiotherapy for ovarian cancer, and the mechanisms by which radiotherapy can mobilise anticancer immunity. We provide emerging preclinical and clinical data for combining immunotherapy with radiotherapy for ovarian cancer treatment and offer a clinical development roadmap to guide the next generation of clinical trials for this combination strategy for this disease.