Endometriosis is a chronic, oestrogen-dependent inflammatory disease characterised by the implantation of endometrial tissue outside the uterine cavity. Pathogenetic factors include immune system dysfunction, angiogenesis disturbances, hormonal imbalance, and genetic predisposition. Key roles are played by activated macrophages and pro-inflammatory cytokines (IL-1, IL-6, TNF-α), as well as an altered Th1/Th2 lymphocyte balance and reduced NK cell activity. Endometriosis significantly reduces the quality of life for patients, affecting their physical, mental, and social well-being. According to the European Society of Human Reproduction and Embryology recommendations, endometriosis treatment should be multifaceted, incorporating hormonal therapy and non-pharmacological methods such as dietary adjustments. Increasing research confirms the positive impact of an anti-inflammatory diet on reducing inflammation and alleviating endometriosis symptoms. Such a diet focuses on consuming foods rich in omega-3 polyunsaturated fatty acids, polyphenols, and terpenes, which have anti-inflammatory and antioxidant properties. The mechanisms of its action include modulating gut microbiota, reducing inflammatory markers (C-reactive protein, IL-6, TNF-α), and regulating oxidative stress. Studies show that women following an anti-inflammatory diet for at least three months experience reduced levels of inflammatory markers and relief from pain symptoms. Key dietary components, such as eicosapentaenoic and docosahexaenoic acids, work by inhibiting arachidonic acid metabolism and synthesising pro-resolving mediators, thereby reducing the production of pro-inflammatory cytokines. Polyphenols and terpenes affect cell signalling pathways and reduce the expression of pro-inflammatory genes. In conclusion, an anti-inflammatory diet is a promising adjunct to endometriosis therapy, helping to reduce inflammation and improving patients’ quality of life. However, further research is needed to determine optimal dietary components and their dosages.