The development of nettle fiber-reinforced polymer composites presents a sustainable alternative to synthetic materials, offering advantages such as biodegradability, recyclability, and reduced environmental impact. The fabrication method, matrix type, and fiber characteristics significantly influence the composite’s mechanical and thermal properties. Techniques like hand layup, melt mixing, extrusion, and injection molding are commonly employed, with fiber orientation and length playing a critical role in load transfer and tensile performance. Thermoplastics (e.g., PLA, PP) and thermosets (e.g., epoxy, polyester) are used as matrices, with PLA gaining attention for its renewability and biodegradability. However, natural fibers like nettle are hydrophilic, leading to poor fiber-matrix adhesion. To address this, chemical (e.g., alkaline, silane) and physical (e.g., plasma, UV) treatments are used to improve surface compatibility. Mechanical studies show optimal performance at 50 wt% fiber loading, beyond which interfacial adhesion weakens. Thermal analysis reveals that nettle fiber composites maintain stability up to 300 °C, with enhanced storage modulus at optimal fiber content. These findings highlight the importance of fiber treatment, matrix selection, and processing methods in designing high performance natural fiber composites for applications in packaging, construction, and automotive sectors.