Breast cancer incidence continues to rise globally, reflecting its heterogeneous and multifactorial nature. Its complexity is driven by molecular subtypes and distinct pathological features. Current therapeutic strategies, though effective for many patients, offer persistent limitations, especially in human epidermal growth factor receptor 2 breast cancer-positive and triple-negative breast cancers, where intratumoral variability and adaptive resistance reduce long-term efficacy. The complex molecular characteristics of these tumours require improved prognostic and preventive intervention such as reliable biomarkers, targeted therapies, and personalised risk assessment. Precision medicine offers a patient-specific framework that integrates genomic profiling, molecular diagnostics, and tailored therapies to address these challenges. Integration of next-generation sequencing and liquid biopsy platforms has enhanced detection, stratification, and longitudinal monitoring in clinical settings. This chapter outlines the molecular landscape of breast cancer, the role of emerging diagnostics, and precision-guided therapeutic approaches in real-time monitoring and disease management. It also reviews ongoing clinical investigations, current challenges, and future directions toward more effective, individualised care.