This research explores the improvement of compatibility between natural reinforcement materials and polymer matrices, specifically focusing on Alfa fiber/polypropylene (PP) composites. The composites are fabricated using both untreated and treated Alfa fibers, with or without the addition of a maleic anhydride grafted polypropylene (MAPP) compatibilizer. The crystallinity increased by 39.7% in composites with chemically treated Alfa fibers compared to untreated ones, and by an additional 13.6% when MAPP was also incorporated. Processing of the composites is carried out through a twin-screw extruder, followed by injection molding. Various characterization techniques are employed to analyze the resulting composites. Thermal analysis demonstrates that the incorporation of chemically treated Alfa fibers with MAPP significantly accelerates the crystallization rate of the PP matrix, suggesting the fibers act as efficient nucleating agents. Additionally, composites with the combined treatment exhibit notable enhancements in flexural properties compared to untreated samples. Scanning electron microscopy (SEM) images of the fractured surfaces further confirm that the interface between the fibers and the PP matrix is improved, especially with the combined treatment.