<p>Natural rubber is a renewable biopolymer valued for its exceptional elasticity, resilience, and mechanical durability, making it an attractive alternative in the expanding landscape of bio-based materials. However, its inherently high molecular weight and limited solubility hinder its direct incorporation into advanced polymer application. A controlled degradation process therefore represents a crucial strategy to transform natural rubber into low-molecular-weight liquid rubbers with tunable reactive functionalities. This review provides a comprehensive overview of established and emerging controlled degradation pathways including mechanical, thermal, oxidative, and photochemical methods while detailing their mechanisms, reaction parameters, and resulting structural characteristics. The chemical oxidative and photochemical approaches had been drawn into attention as they enable selective cleavage of C–C or C = C bonds to yield functional oligomers bearing hydroxyl and carbonyl end groups. Recent advances in photocatalytic and green oxidant systems further highlight the potential for environmentally benign depolymerization. By integrating mechanistic insights, this review underscores controlled natural rubber degradation as a versatile platform for generating functionalized bio-based oligomers suitable for various downstream applications.</p>