Abstract: This study evaluates the impact of a 4-h alkali treatment, using various concentrations of NaOH (2.5%, 5%, 7.5%, 10%, and 15% w/v), on Calamus tenuis cane fibers (CTCFs). Chemical analysis reveals a significant increase in cellulose content, reaching 50.07 ± 1.67% in CTCFs treated with 7.5% NaOH, accompanied by reductions in hemicellulose and lignin as confirmed by FTIR analysis. XRD analysis shows improved structural stability with an enhanced crystallinity index of 44.47 ± 0.69% and crystallite size of 3.03 ± 0.18 nm for CTCFs treated with 7.5% NaOH. TGA analysis indicates decreased activation energy and thermal stability post-treatment. Moreover, CTCFs treated with 7.5% NaOH exhibit peak values of Young’s modulus (2.33 ± 0.05 GPa) and tensile strength (61.37 ± 1.05 MPa). SEM and AFM analyses confirm increased roughness post-treatment, enhancing fiber-matrix interlocking during composite fabrication. EDX analysis identifies an increased O/C ratio post-treatment, suggesting efficient removal of non-cellulosic elements. In conclusion, treating CTCFs with 7.5% NaOH for 4 h at ambient temperature enhances their physicochemical, structural, mechanical, and surface properties, indicating their potential for advanced polymer composites.