Cancer, one of the most lethal diseases, kills millions of people globally and has a significant economic impact. Although immunotherapy, chemotherapy, and surgery have improved, the intricate nature of the tumor microenvironment, the rise of cancer recurrence, their severe adverse effects, and multidrug resistance call for novel therapeutic options. Hydrogels, particularly stimuli-responsive hydrogels (SRH), in light of their high biocompatibility, flexible characteristics, and ability to encapsulate drugs it are gaining popularity as a drug delivery option. SRH has shown considerable potential in enhancing the safety and efficacy in cancer treatment by delivering site-specific drug delivery and reducing the adverse effects. These hydrogels release drugs in reaction to particular biological or environmental stimuli, including light, pH, magnetic fields, temperature, enzymes, and so on. This chapter provides an overview of SRH for treating cancer, its classification, properties, and mechanisms of drug release, reviews literature and recent advancements in hydrogel-based cancer therapy, explores patented technologies and clinically approved treatments, and discusses future prospects, emphasizing their potential in personalized medicine, combinatorial therapies, and nanotechnology integration. By harnessing the unique characteristics of hydrogels, researchers are opening the door for more accurate and effective therapies in the future.