The disposal problems associated with the conventional plastic have imposed a long-standing quest of developing the degradable material. Indeed, blending of conventional plastic with renewable resources as the base materials is an attempt of imparting some level of biodegradability on the resulting composites. Thus, for this study, the effect of plasticized sago starch (plasticized) incorporation on the properties of low-density polyethylene (LDPE)-reinforced with kenaf core fiber (KCF) was evaluated. The ratio of LDPE/KCF was fixed at 80/20 and blended with the thermoplastic sago starch (TPSS) content ranging from 10 to 40 wt%. The blended samples were characterized by means of mechanical performance, Fourier transform infrared analysis, thermogravimetric and differential scanning calorimetry behavior, water uptake, and morphological properties. The experimental result shows that there is a gradual decrease in tensile strength, modulus, and elongation at break with an increase in TPSS loading. The degree of dispersion and adhesion of TPSS in LDPE/KCF composites revealed by scanning electron micrograph supports the findings of tensile properties. The thermal stability of the composite was clearly improved with the addition of TPSS. However, water uptake and hydrophilic character of the composite system tended to augment as the TPSS imparted to the composites.