This chapter explores the role of bionanocomposites, advanced materials that combine renewable, bio-based polymers with nanoscale reinforcements in transforming structural engineering, building, and construction. It reviews the composition and various types of bionanocomposites, highlighting their potential to deliver superior mechanical, thermal, and environmental performance while supporting sustainable green building practices. Bionanocomposite materials hold promises for specific applications in the building sector, including lightweight concrete, thermal insulators, and retrofitting solutions for commercial housing and infrastructure projects, aligning with sustainable development goals 9, 11, and 12. The chapter also examines different innovative manufacturing techniques with a focus on green methods, such as sonochemical processing, in-situ polymerization, layer-by-layer assembly, electrospinning, melt compounding, and the sol–gel process, and assesses their advantages and shortcomings. Furthermore, the chapter explores diverse applications ranging from enhanced structural components, improved insulation and thermal regulation, and advanced coatings and finishes to self-healing materials and smart structural monitoring systems that collectively contribute to energy efficiency, durability, and reduced environmental impact. By integrating cutting-edge research with practical case studies, this chapter elucidates the potential of bionanocomposites to play a pivotal role in the development of eco-friendly, resilient infrastructure aligned with sustainable development goals.