Carbohydrate-based hydrogels represent a new advancement in the development of multifunctional biomedical systems, thanks to their intrinsic biocompatibility, structural versatility, and capacity for functional modification. This review examines the latest progress made in employing these materials as intelligent theranostic platforms, with a particular focus on their role as biosensors and therapeutic drug delivery devices. Engineered to interact dynamically with the biological environment, carbohydrate hydrogels enable the site-specific release of therapeutic agents while simultaneously supporting the monitoring of key physiological markers. Their dual functionality offers significant advantages in managing complex pathologies such as cancer, metabolic disorders, and chronic inflammation, where personalized treatment and real-time feedback are essential. By exploring their biological application, this review underscores the pivotal role played by carbohydrate hydrogels in advanced therapeutic technologies.