Huge polymer waste is currently the largest threat to the world. Extensive research is needed to develop various techniques for utilizing large amounts of polymer waste in beneficial ways. The road industry serves as an optimal sector for incorporating various waste polymers in the construction of flexible pavement. A variety of polymers have been proven as a potential modifier to improve the strength, stability, and durability of asphalt due to better resistance of bitumen to various distresses, such as rutting, fatigue, and thermal cracking. This study explores technical aspects and highlights the effects of several types of polymer addition in bitumen and its effects on both bitumen and asphalt. Additionally, the review discusses the compatibility, challenges, and prospects of polymer-modified bitumen. This study examines the impact of plastomeric polymer additives on the physical, rheological, and thermal properties of bitumen, providing a detailed comparison of their influence on the performance characteristics of asphalt mixtures. Studies show that adding 2–8% polymer by bitumen weight enhances asphalt stiffness, but mixing and storage methods greatly affect binder stability. The paper provides useful insights and recommendations for the design, construction, and maintenance of flexible pavements using polymer waste as a modifier in bitumen.