This review article discusses the sustainability of natural-fiber-reinforced polymers (NFRCs) in the context of environmental impact and their potential applications in engineering. The article highlights the importance of balancing the mechanical performance and biodegradability of composites to achieve an environmentally conscious design. It covers the sustainability aspects of NFRCs at various stages, including materials, performance, applications, and end-of-life. The review also explores different types of sustainable natural fibers and polymer resins, along with recent advancements in the mechanical and functional properties of these composites. The potential applications of NFRCs across diverse engineering fields are also discussed. Natural fibers such as flax, jute, coir, hemp, and kenaf are used as reinforcement in composites, offering advantages such as cost-effectiveness, good thermal and acoustic insulation properties, and biodegradability. However, the mechanical performance of natural fiber composites is generally lower than that of synthetic fiber composites like glass or carbon fiber composites. To improve the mechanical properties of NFRCs, nanomaterials such as metal oxides, carbon nanotubes, and graphene are often added. The review also discusses the sustainability of thermoset and thermoplastic matrices used in composites. Thermoset matrices, such as epoxy, vinyl ester, and unsaturated polyester, are widely used due to their excellent mechanical properties and dimensional stability. However, they are not easily recyclable and have a significant environmental impact. In contrast, thermoplastic matrices, such as polypropylene and polyethylene, are more recyclable and have a lower environmental footprint. The review highlights the importance of developing sustainable, biodegradable, and recyclable composites to reduce the environmental impact of traditional synthetic composites. The article also discusses the performance of sustainable composites, noting that while they may have lower mechanical performance compared to synthetic composites, they offer significant environmental benefits. The performance of sustainable composites can be improved through various methods, including fiber orientation, surface treatment, and the use of nanomaterials. The review also highlights the applications of sustainable composites in various industries, including automotive, aerospace, marine, and construction. The use of natural fiber composites in these industries is increasing due to their favorable mechanical properties, cost-effectiveness, and environmental benefits. The review concludes that sustainable composites have the potential to serve as alternatives to traditional synthetic composites, reducing environmental impact and promoting a more sustainable future.This review article discusses the sustainability of natural-fiber-reinforced polymers (NFRCs) in the context of environmental impact and their potential applications in engineering. The article highlights the importance of balancing the mechanical performance and biodegradability of composites to achieve an environmentally conscious design. It covers the sustainability aspects of NFRCs at various stages, including materials, performance, applications, and end-of-life. The review also explores different types of sustainable natural fibers and polymer resins, along with recent advancements in the mechanical and functional properties of these composites. The potential applications of NFRCs across diverse engineering fields are also discussed. Natural fibers such as flax, jute, coir, hemp, and kenaf are used as reinforcement in composites, offering advantages such as cost-effectiveness, good thermal and acoustic insulation properties, and biodegradability. However, the mechanical performance of natural fiber composites is generally lower than that of synthetic fiber composites like glass or carbon fiber composites. To improve the mechanical properties of NFRCs, nanomaterials such as metal oxides, carbon nanotubes, and graphene are often added. The review also discusses the sustainability of thermoset and thermoplastic matrices used in composites. Thermoset matrices, such as epoxy, vinyl ester, and unsaturated polyester, are widely used due to their excellent mechanical properties and dimensional stability. However, they are not easily recyclable and have a significant environmental impact. In contrast, thermoplastic matrices, such as polypropylene and polyethylene, are more recyclable and have a lower environmental footprint. The review highlights the importance of developing sustainable, biodegradable, and recyclable composites to reduce the environmental impact of traditional synthetic composites. The article also discusses the performance of sustainable composites, noting that while they may have lower mechanical performance compared to synthetic composites, they offer significant environmental benefits. The performance of sustainable composites can be improved through various methods, including fiber orientation, surface treatment, and the use of nanomaterials. The review also highlights the applications of sustainable composites in various industries, including automotive, aerospace, marine, and construction. The use of natural fiber composites in these industries is increasing due to their favorable mechanical properties, cost-effectiveness, and environmental benefits. The review concludes that sustainable composites have the potential to serve as alternatives to traditional synthetic composites, reducing environmental impact and promoting a more sustainable future.