In recent years, there has been much effort to find cost-effective ways to replace petroleum-based commodity plastics with biodegradable polymers with comparable thermal characteristics. The 5 wt.%, 10 wt.%, and 15 wt.% kenaf fiber were melted, and blended with polyamide-6 via a Brabender mixer, followed by compression molding. To evaluate the thermal properties of composites, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic thermomechanical analysis (DMA) were conducted. According to the TGA results, increased kenaf fiber contents decreased the composite’s thermal stability. Neat PA6 matrix decomposed rapidly at 425°C, which was comparatively higher than PA6 composites. From the DSC analysis, the addition of natural fibers resulted in quantified changes in the glass transition temperature (Tg), melting temperature (Tm), and crystallization temperature (Tc) of the PA6 composites. According to the DMA, the storage modulus of neat PA6 was 1177 MPa and decreased to 1076 MPa for 5 wt% of kenaf fiber in PA6 composite. The Kenaf fiber/polyamide 6 composites appeared to have lower thermal stability than neat PA6. This study demonstrated that the kenaf fiber/polyamide 6 composites were successfully prepared, and a detailed thermal analysis was conducted. Improving the KF/PA6 composites can be further studied to increase thermal stability.