Cancer remains a major global health burden, necessitating precise and effective therapeutic strategies. Nanotechnology-based interventions have enabled targeted drug delivery, with dendrimers emerging as promising nanocarriers due to their defined architecture, multivalency, and capacity for drug encapsulation or conjugation. Stimuli-responsive dendrimers allow controlled drug release in response to specific internal stimuli—such as pH shifts, redox conditions, and enzyme activity—or external triggers including light, temperature, and magnetic fields. These systems are designed to exploit the pathological characteristics of tumor microenvironments, such as acidic pH, elevated glutathione levels, and enzyme overexpression, to achieve selective drug release. Various chemical linkages and functional moieties are incorporated to render dendrimers responsive to individual or multiple stimuli. Thermo-responsive dendrimers utilize phase transitions near body temperature, while light-responsive systems enable on-demand release using photo-cleavable groups. Multi-stimuli-responsive designs further enhance targeting efficiency by addressing tumor heterogeneity. This chapter highlights the design principles, release mechanisms, and therapeutic outcomes of such systems, supported by in vitro and in vivo studies. Despite encouraging outcomes, challenges related to in vivo stability, biocompatibility, and clinical scalability persist. Continued research is essential to optimize dendrimer architecture and integrate diagnostic functionality for effective clinical translation in oncology.