The physical and tensile analysis of NaOH-treated Borassus fibers is carried out to expand and open up further possibilities for their use as reinforcement in composites. This study will describe the NaOH treatment procedure on fibers utilizing the batch reactor approach, as the soaking method is typically used in this case. The physical analysis shows that the wettability behavior effect of NaOH was led by using 5%, 10%, and 15% of NaOH solutions. The result of each treatment using NaOH was then characterized by using SEM-EDX to show the morphology and mechanical properties of the material before and after alkali treatment. Otherwise, FTIR was used to identify the functional group before and after alkali treatment. The tensile properties of the Borassus fibers (raw and treated) were also discussed. The wettability test was carried out by using the contact angle measurement technique. All samples (natural and treated fibers) showed a contact angle of less than 90°, which is associated with the hydrophilic surface properties. This result indicated that this treated fiber has polar properties. The increase of NaOH percentage in the treated samples caused a decrease in the contact angle. This phenomenon was related to the SEM image of natural and treated fibers. SEM result shows the cleaning effect of nonpolar components from the fiber surface and the roughening of the surface during the NaOH treatment. The result of FTIR indicates that several functional group components, such as impurities, lignin, and hemicellulose, were leaching out from row fibers after alkali treatment. The mechanical test results indicate improved tensile properties due to the NaOH treatment. Moreover, the samples from the fiber treated with 10% NaOH indicated the highest tensile strength.