Stimuli-responsive, cell-mediated drug delivery systems represent a dynamic interface between biological functionality and engineered control. Leveraging the inherent targeting properties of erythrocytes, immune cells, stem cells, and exosomes, these systems offer a promising strategy for precise therapeutic delivery. In this review, we provide a comprehensive analysis of the design principles and biological underpinnings of stimuli-responsive carriers that release payloads in response to endogenous triggers (e.g., pH, redox, enzymatic activity) or external stimuli (e.g., light, ultrasound, magnetic fields). We further examine current strategies for loading and functionalizing cellular carriers, highlight key therapeutic applications across oncology and regenerative medicine, and assess translational progress and regulatory challenges. This review underscores the emerging clinical potential of intelligent cell-based delivery vehicles and outlines future directions for their optimization and implementation.