<p>Composite and nanocomposite polymers are revolutionizing structural applications across aerospace, automotive, and construction industries by offering superior performance characteristics. Recent advancements have enabled significant enhancements in strength-to-weight ratios, thermal stability, and durability, addressing critical engineering challenges. In aerospace, these materials have facilitated up to a 20% reduction in structural weight, resulting in improved fuel efficiency and payload capacity. Automotive applications have achieved a 50% reduction in weight using carbon fiber-reinforced polymers, directly enhancing fuel economy and performance. Similarly, construction innovations incorporate self-healing and 3D-printed composites, promoting sustainability and extended lifespan. This study highlights groundbreaking developments in manufacturing techniques, such as in-situ polymerization and additive manufacturing, that optimize material properties and scalability. Novel reinforcement strategies, including functionalization and hybridization, have demonstrated a tensile strength increase of up to 80% with minimal filler content. Additionally, advanced nanotechnology integrations improve barrier properties and thermal stability, broadening the materials’ applicability in high-performance environments. Through comprehensive case studies and a forward-looking discussion on challenges, this paper underscores the transformative role of composite and nanocomposite polymers in structural engineering, paving the way for future innovations that align with evolving industrial and environmental demands.</p> Graphical abstract <p></p>