This review explores the current state and future potential of bioplastics as sustainable alternatives to conventional fossil-based polymers. It provides a detailed examination of the classification, molecular structures, and synthetic routes of major bioplastics, including polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene adipate-<i>co</i>-terephthalate (PBAT), and polyhydroxyalkanoates (PHAs). Special emphasis is placed on the unique properties and degradation behaviors of each material across various environmental conditions, such as industrial composting, soil, and marine ecosystems. The manuscript further discusses advanced strategies in polymer design, such as copolymerization, reactive blending, and incorporation of nano- or micro-scale additives, to enhance flexibility, thermal resistance, barrier properties, and mechanical integrity. In addition to technical advancements, the review critically addresses key limitations impeding large-scale commercialization, including high production costs, limited availability of bio-based monomers, and inadequate end-of-life treatment infrastructure. Finally, future research directions are proposed to advance the development of fully bio-based, functionally tunable, and circular bioplastics that meet the performance demands of modern applications while reducing environmental impact.