Interests in the use of natural fibers-fillers in composite materials are growing rapidly due to the low cost and high availability. However, poor surface adhesion and mineralization are the main drawbacks that restrict the use of natural fibers in different applications. Thus, it is essential to perform a treatment that can improve the surface properties of natural fibers before being used in the composites. Such treatments are physical (corona, plasma, etc.), chemical (alkaline, silane, acetylation, etc.), and biological (enzyme), but the benefits of each treatment considering energy consumption and effluent generation should be considered more in-depth. Via a literature review, this study investigated the mechanical performance, energy consumption, and generated effluents of chemical treatments (silane, alkaline, acetylation, and maleated coupling) as the consequence of fiber treatment to propose a more sustainable treatment at the scope of the treatment section in the factory of natural fibers-polymer composites (gate to gate). It was shown during this review study that the maleated coupling is a more sustainable method since it needs no specific energy during the treatment while produces no effluent and improves the mechanical strength performance of the composites more constantly.