The current work focuses on the mechanical, fatigue, and water absorption behavior of Cissus quadrangular natural fiber (CQF) with leftover Limonia acidissima shell powder (LPA) in an epoxy matrix. Creating a sustainable biocomposite for use in high-tech engineering that uses recycled reinforcements generated from agricultural waste was the main objective of this research. An amino silane was applied to the natural fibers and particles to improve the connection between the matrix and those components. The composites were made using the hand lay method, and they were characterized using ASTM criteria. The results show that boosting the CQF volume lengthens the fatigue lifetime by as many as 36,471 life counts. The tensile strength was improved by 59% with the addition of 30 vol.% CQF. Similar morphological studies were carried out with scanning electron microscopy on the broken surfaces of composites (SEM). It demonstrates how the addition of Limonia acidissima microparticles to epoxy composites can improve the surface modification of the fiber and matrix. However, the water-absorbing behavior was only slightly enhanced by the addition of cellulosic fiber and LAP particles. The findings of this characterization study support the usage of surface-modified Cissus quadrangularis fibers and Limonia acidissima powder to create lightweight epoxy composites in a variety of industrial contexts.