The pursuit of sustainable materials in construction has led to increased interest in bio-based materials for structural applications. This review paper examines the mechanical performance of structural members made from bio-based materials, including natural fibres, bio-based polymers, and engineered wood products. Key mechanical properties such as tensile, compressive, and flexural strength, as well as durability under environmental stressors, are analyzed to understand their suitability for load-bearing applications. The paper also discusses factors affecting mechanical behaviour, including moisture absorption, temperature sensitivity, and fabrication techniques. A comparative analysis highlights the performance of bio-based materials against conventional materials like steel and concrete, emphasizing both their strengths and limitations. Enhancements in bio-based composites, including hybridization and nanotechnology, are reviewed for their potential to improve mechanical robustness. Additionally, sustainability aspects, such as life cycle assessment and end-of-life biodegradability, are evaluated to underscore the environmental benefits of bio-based structural members. The paper concludes with future research directions, advocating for innovation in bio-based material technology to meet structural demands and support the construction industry's shift toward greener practices. This review aims to provide a foundational understanding for engineers and researchers seeking to integrate bio-based materials into sustainable structural designs.