Cancer is a complex and multifaceted, significant global challenge. The quest for a perfect and universally effective therapy for cancer remains elusive. In recent years, transformative advances have emerged in cancer therapy. Nanoparticles offer precise treatment and alternative chemotherapeutics. With the limitations of nanocarrier systems, stimuli-responsive nanoparticles garnered significant interest in cancer therapy, with target site specificity in addition to on-demand and handy spatiotemporal control over the drug release of anticancer agents in specific tumor sites. There are diverse stimuli speculated to promote anticipated activities, which were sorted as external and internal stimuli. The external stimuli include ultrasound, light, thermoresponsive, magnetic, and electric fields, whereas the internal stimuli bring in enzyme sensitivity, pH variations, and redox reactions. Internal stimuli response nanoparticles dynamically adapt to conditions, activated by variations in physiological pH, redox potential of cells, and enzyme-sensitive stimuli. Ultrasound-responsive nanoparticles permit non-invasive, spatially controlled release, particularly in photothermal therapy light responsive counterparts provide precise control of drug release and imaging. Nanoparticles undergo structural alterations with temperature to achieve thermoresponse. Externally directed magnetic field-responsive nanoparticles, targeted delivery to intricate biological systems. Preclinical studies bridge the gap between innovative stimuli-responsive nanosystems and potential clinical applications, pioneering the future of cancer therapy. Testing the stimuli-responsive nanosystems in animal models (In-vivo) and controlled laboratory settings, like in cells (in vitro). This chapter will emphasize precisely the preclinical studies in the design and development of stimuli-responsive nanosystems as a promising chemo-therapeutic option in different cancer types, along with the future perspective and challenges. Stimuli-responsive nanoparticles showed promise in the treatment of breast cancer, colorectal, lung, and gastrointestinal delivering therapeutic drugs specifically with precision and causing the least collateral damage. Studies also demonstrated the effectiveness of the most aggressive cancer, like glioblastoma multiforme.