The transportation industry is undergoing a paradigm shift toward sustainability, driven by environmental concerns and regulatory mandates aimed at reducing greenhouse gas emissions and plastic waste. In this context, biodegradable materials derived from renewable biological sources are emerging as viable alternatives to conventional petroleum-based polymers traditionally used in vehicle manufacturing. These bio-based polymers—such as polylactic acid (PLA), polyhydroxyalkanoates (PHAs), starch-cellulose composites, and protein-based thermoplastics—are being integrated into interior, exterior, and structural components of both automotive and aerospace vehicles. Their biochemical properties enable tailored degradation pathways through hydrolysis and microbial action, aligning with circular economy goals and lifecycle sustainability. This chapter provides an in-depth exploration of the molecular structure, synthesis routes, degradation mechanisms, and engineering applications of these materials in modern vehicle design. It also addresses current challenges such as performance limitations, scalability issues, feedstock competition, and end-of-life infrastructure gaps. Emerging trends—including genetic engineering for enhanced PHA production, nanotechnology integration, enzymatic recycling, and bio-inspired composite development—are discussed in detail. The chapter concludes with insights on how advances in biochemistry and industrial ecology can drive the future of sustainable mobility. By leveraging innovations in polymer science, microbiology, and green chemistry, the automotive and aerospace industries are poised to transition toward more environmentally responsible material systems that meet the functional demands of high-performance vehicles.