Cancer remains one of the most prominent global health concerns, posing a substantial threat to public health. Millions of people die from cancer each year, and many cancer types remain incurable at present. Conventional cancer treatments, including surgery, chemotherapy, radiotherapy, and immunotherapy, often fail to achieve optimal clinical outcomes and are frequently associated with severe trauma and adverse effects. Consequently, there is an urgent need to develop novel therapeutic strategies to address these limitations. Hydrogels have been widely utilised as platforms for loading drugs, proteins, DNA, and stem cells in biomedical tissue repair and cancer therapy. Through modification of their physicochemical properties and functions, hydrogels can be endowed with responsiveness to multiple stimuli. In recent years, stimuli-responsive hydrogels (also known as smart-responsive hydrogels), as novel drug delivery systems, have demonstrated remarkable efficacy in cancer treatment. Stimuli-responsive hydrogels are capable of altering their mechanical properties, swelling behaviour, hydrophilicity, bioactivity, and molecular permeability in response to endogenous stimuli (including pH, ROS, and temperature) and exogenous stimuli (including light, ultrasound, and magnetic fields). This review highlights recent advances and applications of responsive hydrogels triggered by endogenous stimuli (including pH, ROS, and temperature) and exogenous stimuli (including light, ultrasound, and magnetic force) in cancer drug delivery and treatment. Finally, the current application limitations and future prospects of smart-responsive hydrogels are summarised.