Investigations on alternative asphalt additives have been initiated by the growing need for environmentally friendly materials. Waste materials have been introduced in recent years to modify the asphalt. In this research work, waste plastic and rubber seeds are utilized to prepare the char. This study aims to compare the effectiveness of plastic char and biochar as a partial replacement for asphalt binder while assessing the resultant binder’s various physical, and mechanical characteristics. Pyrolytic char and biochar are substituted for asphalt binder in different proportions: 5, 10, and 15% by weight due to their superior performance even at higher replacement percentages. Physical characteristics including ductility, penetration, softening point, elastic recovery, and storage stability are measured on char-modified asphalt binder. The binder becomes stiffer with the addition of char. For assessing the stiffness of the binder, rheological performances are also determined. Tests such as Marshall stability, indirect tensile strength (ITS), and tensile strength ratio (TSR) are carried out to investigate the mechanical characteristics of the asphalt mix in further detail. Throughout, the test findings demonstrate that adding plastic char makes the binder stiffer more than adding biochar. In comparison to virgin asphalt binder, plastic char with a 5% replacement and biochar with a 10% replacement exhibit superior mechanical characteristics.