Hydrogels with exceptional water-retention capabilities, have emerged as pivotal biomaterials in the biomedical field, offering a transformative approach to addressing challenges in medicine and drug delivery. Their biocompatibility, tunability, and responsiveness to environmental stimuli position them as ideal candidates for encapsulating and releasing therapeutic agents in a controlled manner. Among these, stimuli-responsive hydrogels have demonstrated remarkable potential, responding to specific triggers such as pH, temperature, or enzymatic activity, enabling site-specific and on-demand drug release. This review synthesizes recent advancements in hydrogel technologies, focusing on their chemical composition, mechanisms of action, and innovative applications in the biomedical domain. It further explores emerging trends such as hybrid hydrogels that integrate synthetic and natural polymers to optimize performance, as well as hydrogels augmented with nanoparticles for enhanced functionality. While highlighting the achievements, the review also addresses existing challenges, including mechanical stability and degradation control, and proposes directions for future research. By providing a comprehensive analysis of the current state and potential of hydrogels, this review underscores their critical role in advancing modern medicine and drug delivery systems, bridging the gap between laboratory innovation and clinical application.