This chapter presents a comprehensive overview of cutting-edge nanoscale technologies that are transforming breast cancer detection, monitoring, and treatment. We begin by exploring nanobiosensors and their fundamental role in early diagnosis, followed by recent advancements in imaging modalities enhanced by optical and magnetic nanoparticles. The integration of triboelectric nanogenerators (TENGs) for cancer prevention and therapy is also discussed, highlighting their potential in energy harvesting and localized treatment. In addition, a major focus is placed on high-throughput microarray analysis, detailing each experimental stage from RNA extraction to bioinformatics-driven gene classification, and its application in identifying breast cancer subtypes and signatures. Moreover, the chapter reviews the synergistic application of nanomaterials in quantitative real-time PCR (qPCR), discussing how various nanoscale platforms—such as metallic, magnetic, carbon-based, and polymeric nanoparticles—overcome limitations of conventional methods and enhance diagnostic sensitivity and specificity. We further delve into the emerging “tumor-on-a-chip” (TOC) platforms, emphasizing fabrication methods, material selection, and their role in recapitulating tumor microenvironments for drug screening and mechanistic studies. Micro- and nanofluidic systems for in situ tumor cell analysis are also examined, with particular attention to circulating tumor cell (CTC) separation, electrochemical biosensing, and intracellular biomarker profiling. This chapter offers a multidisciplinary perspective bridging nanotechnology, molecular diagnostics, and bioengineering, and underscores the transformative impact of nanoscale technologies on personalized breast cancer medicine.