Extracellular vesicles/exosomes (EVs), in particular, are stimuli-responsive nanosystems that have shown effect in cancer treatment due to their biocompatibility and capacity to transport bioactive materials. This chapter provides a thorough overview of the EVs’/exosomes’ biogenesis, composition, isolation techniques, and stimuli-responsive characteristics. Different EV subtypes are described, such as oncosomes, apoptotic bodies, migrasomes, and ectosomes; exosomes are discussed in particular because of their importance in intercellular communication. The preparation and separation procedures for EVs, including density gradient ultracentrifugation, differential centrifugation, polymer precipitation, and microfluidics-based approaches, are elaborated upon, with a focus on the significance of isolation techniques in preserving the integrity and functionality of EVs. The chapter also describes the stimuli-responsive characteristics of EVs/exosomes, both exogenous (such as light, magnetic field, temperature, and ultrasound responsiveness) and endogenous (such as enzyme, pH, and redox responsiveness), emphasizing their potential for precise and regulated drug administration. It also looks at how stimuli-responsive EVs/exosomes are used in cancer therapy, including drug administration, immunotherapy, gene therapy, and diagnostic imaging, showing how important they are to the development of individualized and successful cancer treatment plans.