Adhesively bonded joints are structural connections that are widely used due to their lightweight, efficient, and versatile bonding capabilities. However, its reliability is severely affected by the high and complex stress fields present at the overlap ends. The present study aims to enhance the strength of adhesively bonded joints by incorporating sustainable materials, specifically fibers extracted from pineapple leaf fiber (PALF) and Jute, into the adhesive matrix as reinforcement. A three-dimensional numerical analysis is performed, employing Araldite 2015 adhesive to join metallic plates. The fibers are oriented along the loading direction, and a parametric investigation is conducted to optimize the fiber density within the adhesive region. A comparative analysis is performed considering the fiber positioning and spacing, to effectively mitigate stress concentration at the overlap ends. Joint failure is computed for lap joint without fibers and compared with closed form solutions from the literature. The results demonstrate that the incorporation of PALF and Jute fibers substantially reduces stress concentrations at the overlap ends, thereby enhancing the load-bearing capacity of the joints. The methodology and results emphasize the effectiveness of the use of sustainable materials in engineering applications that results in enhancing the strength of adhesively bonded joints.