Recycling of waste plastics (WP) denotes an effectual method to dispose the post-consumer products for possible alternative way to obtain new materials with good properties. With this aim the influences of WP and maleic anhydride (MA) grafted WPs (MA-g-WP) were investigated as the bitumen modifiers for paving applications. Fourier transform infrared (FTIR) spectroscopy analysis established the effective grafting of MA with the waste plastic (WP). Polymer modified bitumen (PMB) binders were analyzed under scanning electron microscopy (SEM) and optical microscopy (OP) in an effort to characterize the bitumen/modifier interphase morphology. The conventional rheological tests such as penetration test, softening point, and ductility results indicate that the degree of polymer modifications are function of the nature of modifier, bitumen–modifier compatibility, and modifier concentration. It has also been confirmed that the morphology observed by SEM and optical microscopy revealed the compatibility between MA-g-WP and bitumen, and the storage stability of binder was improved significantly compared with WP modified bitumen (WPMB) binders. Consequently, the use of grafted modifier with polar site can be considered as a suitable alternation for modification of binder in pavement by expecting their chances for better performance during service.