Developing composites using fabrics made from natural fibers represents a sustainable alternative for civil construction. Ensuring adequate interaction between the components is essential for the proper performance of the composite, preventing premature failure. This study analyses the interaction between jute and sisal fabrics with a cementitious matrix. The adhesion between natural fibers and the cementitious matrix is directly influenced by factors such as the attack of free hydroxides from cement, impurities from the production process, and water absorption capacity of the fibers. The fibers were treated using a cyclic hornification process to mitigate these effects. Additionally, a self-compacting cementitious matrix was used, in which part of the clinker was replaced with fly ash and silica fume. The interaction between fibers and matrix was evaluated through pull-out tests, allowing for comparing results obtained with treated and untreated fibers. The results indicated that sisal adhesion stress was exceeded, leading to the fibers being pulled out of the matrix. Conversely, jute fibers exhibited superior adhesion to their tensile strength, resulting in filament rupture before significant slippage occurred. Hornification treatment positively influenced the adhesion results. Treated fibers demonstrated reduced water absorption capacity, which minimized dimensional variations compared to untreated fibers, contributing to a more stable interaction with the cementitious matrix.