In view of no reports on natural fiber reinforced functionalized styrene acrylonitrile composites, this study develops kenaf fiber (KNF) reinforced chemically functionalized styrene acrylonitrile (CF-SAN) composites (KNF/CF-SAN) by extrusion and injection molding. The selected CF-SAN matrix is a chemically functionalized random ter-polymer, with high (10 ± 2%) maleic anhydride functionality and requires higher processing temperature. With respect to CF-SAN, the 10/90, 20/80 and 30/70 KNF/CF-SAN composites show 25%, 46% and 75% higher tensile modulus, 23%, 55% and 78% higher tensile strength, 34%, 66% and 104% higher flexural modulus and 48%, 87% and 125% higher flexural strength. Relative to the dry matrix, the water absorbed composites show higher properties, but relative to the respective dry composites, the water absorbed composites have at least 7% lower tensile strength and at least 20% lower tensile modulus, flexural modulus and flexural strength. SEM and FTIR (ATR-IR) establish that hydrogen bonding and esterification by Palsule process impart CF-SAN/KNF adhesion and bonding in the composites. The composites show thermal stability between KNF reinforcement and CF-SAN matrix upto 295°C.