Oral drug delivery remains the most widely preferred route for pharmaceutical administration due to its ease of use, cost-effectiveness, and high patient compliance. However, several challenges, including poor drug solubility, limited permeability, enzymatic degradation, and variable gastrointestinal (GI) conditions, can impact the bioavailability and therapeutic efficacy of orally administered drugs. To address these limitations, formulation scientists have explored the use of natural polymers as excipients in oral drug delivery systems. Natural polymers, derived from plant, animal, and microbial sources, offer unique advantages such as biocompatibility, biodegradability, mucoadhesiveness, and functional versatility. Their ability to modify drug release profiles, enhance stability, and improve targeted delivery has made them indispensable in modern pharmaceutical formulations. These biopolymers function as controlled-release matrices, bioadhesive agents, stabilizers, and drug carriers, contributing to sustained and site-specific drug release while minimizing systemic side effects. This chapter provides an in-depth exploration of the role of natural polymers in oral drug delivery, highlighting their diverse applications and advantages over synthetic counterparts. Key natural polymers such as chitosan, alginate, cellulose derivatives, and gelatin are discussed in terms of their physicochemical properties and pharmaceutical applications. Additionally, emerging trends and sustainability aspects of natural polymer utilization are examined, emphasizing their potential in advancing eco-friendly and effective drug delivery strategies. The use of natural polymers aligns with the growing global focus on green pharmaceutical technologies, providing safer, sustainable, and efficient alternatives for improving oral drug delivery systems.