AbstractThis research focuses on developing a new material by reinforcing chemically treated Calotropis gigantea bast fibers (CG) with epoxy resin as matrix. Composites using varying wt% of treated CG fibers were fabricated taking epoxy as matrix. The effect of chemical treatment and fiber loading on various mechanical properties, thermal, water absorption properties, and morphology using scanning electron microscope (SEM) were investigated. An increasing trend in the values of mechanical properties was observed till optimum fiber loading and then declines. The optimum properties were found at 20 wt% of fiber loading. At this fiber loading the composites were characterized by Fourier transforms infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetric (TGA) and compared with untreated fiber reinforced composites and neat epoxy. When comparing untreated and treated composites, it was discovered that composites containing 20% treated CG fibers produce better outcomes. The findings provide manufacturers and engineers with a general concept of how to employ the composites to make low‐weight automotive parts for improved fuel efficiency.