Cancer continues to be one of the main causes of global death, with a continuous increase in mortality and higher incidence. Conventional therapies like chemotherapy, radiation, and surgery, while widely used, often come with substantial side effects and lack the specificity needed to spare healthy tissues. Recent years have witnessed a significant growth in the field of nanomedicine in the field of cancer imaging and treatment. These nanomedicine offers the potential for highly targeted drug delivery, reduced toxicity, and enhanced diagnostic precision. This chapter explores the diverse landscape of nanomaterials—from polymer-based nanoparticles to liposomes and inorganic NPs—and their applications in cancer diagnostics and therapy. It also discusses the mechanisms that make these nanoparticles effective, such as the enhanced permeability and retention (EPR) effect. We also discuss key preclinical design considerations, including tumor heterogeneity, the influence of the microbiota, and age- and sex-based differences. Additionally, we review the regulatory frameworks and translational hurdles, as well as selected cases in which nano-pharmaceuticals have successfully advanced from bench to bedside. In the last section, we briefly discuss some of the possible future directions for the field, like the integration of AI, stratification of patients, and the simplified design of these nanocarriers. Bridging the gap between research and clinical implementation will require not only innovation but also a strategic and patient-centric approach across research, regulation, and clinical practice.