Natural fiber-reinforced composites have garnered significant attention from researchers seeking to produce environmentally friendly materials and promote sustainable industrial development. The characteristics of the final composites, tailored for specific applications, depend not only on the properties of their constituents but also on the fiber/matrix interface. This is why soft fiber treatments are often recommended. This study aimed to assess the influence of the introduction of date palm fibers, having undergone an enzymatic treatment, on the mechanical characteristics of PBS/palm fiber biocomposites. The optimal enzymatic fiber treatment method and duration were determined based on reducing sugars released analysis. Fiber structure changes were determined by spectroscopic and morphologic analysis. The results showed that combined treatment with xylanase and pectinase for 8h contributed to higher amounts of reducing sugars released, indicating efficient removal of hydrophilic fractions. Microstructure tests showed an exposure of cellulose micro-fibrils that could enhance interfacial interaction fiber/matrix in the composite. Mechanically, composites with enzymatically treated fibers exhibited significantly increased stiffness modulus compared to the case of untreated fibers. The improvement in the composites rigidity is explained by the increase in the fibers cellulose rate with the biological treatment, which acts on the non-cellulosic components. The enzymatic treatment maintained the fibers natural morphology, enhancing fiber/matrix adhesion through increased contact surfaces.