Organic core–nonmagnetic shell nanoconstructs represent a cutting-edge approach in cancer theranostics, combining targeted drug delivery with diagnostic capabilities. These nanoconstructs feature an organic core, serving as the primary drug carrier, encapsulated by a nonmagnetic shell that enhances stability and bioavailability and reduces toxicity. The core–shell structure allows for the controlled release of therapeutic agents, minimizing off-target effects and improving treatment efficacy. By incorporating targeting ligands like antibodies and peptides, the nanoconstructs exhibit high specificity for cancer cells, ensuring that the drugs accumulate at the tumor site. Additionally, stimuli-responsive elements, such as pH- or temperature-sensitive triggers, enable precision drug release within the tumor microenvironment. Their theranostic potential is further enhanced by the integration of imaging agents for real-time monitoring via techniques like MRI or fluorescence imaging, offering personalized treatment options. This chapter explores the design, functionalization, and application of these nanoconstructs, along with the challenges and future directions in personalized cancer therapy and beyond.