This review explores the multifaceted relationship between dietary factors and breast cancer outcomes, focusing on unsaturated fats, the Mediterranean diet (MD), and other nutritional components. Breast cancer remains a significant global health concern, with lifestyle factors like diet playing a pivotal role in prevention and management. The review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Articles written in English and released between 2019 and 2024 were acceptable. We used pertinent search terms such as "unsaturated fats", "Mediterranean diet", "breast cancer", and "nutrition" to perform searches in PubMed, PubMed Central (PMC), EBSCOhost, and grey literature such as Google Scholar. After screening, 11 of the 479 original papers were chosen and included in the final review. These include cross-sectional analysis and systematic review, cohort study, narrative review, systematic review and meta-analysis, case-control study, randomized controlled trials (RCTs), and cross-sectional study. Key findings suggest that adherence to the MD correlates with improved quality of life measures and reduced mortality rates among women with breast cancer, particularly in older age groups. The diet's emphasis on antioxidant-rich foods, anti-inflammatory compounds, and healthy fats contributes to these observed benefits. Specific unsaturated fats, notably omega-3 polyunsaturated fatty acids (PUFAs) like docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), demonstrate anti-cancer properties by modulating cancer cell behavior and enhancing treatment responses. Biomarkers associated with the MD, such as β-carotene and lycopene, serve as indicators of dietary compliance and potential risk reduction. Furthermore, components found in olive oil, including polyphenols and monounsaturated fatty acids, exhibit promising effects in preventing breast cancer by exerting antioxidant and anti-proliferative actions. Other dietary factors like calcium, legumes, fruits, and vegetables also play a role in reducing breast cancer risk and improving survival rates. This review underscores the importance of dietary interventions in optimizing outcomes for breast cancer patients and highlights the need for further research to elucidate underlying mechanisms and refine dietary recommendations.