This review highlights the effects of adding to asphalt binder and asphalt mixtures, emphasizing its growing adoption globally due to environmental and economic advantages. The analysis evaluates the performance of asphalt binders and concrete mixtures modified with different forms of polyethylene (PE), including low-density polyethylene (LDPE) and high-density polyethylene (HDPE). The review revealed that incorporating waste polyethylene significantly enhances key properties of asphalt mixtures. Specifically, PE addition increases the softening point, viscosity, and specific gravity while reducing penetration. Furthermore, it improves the complex shear modulus, thermal stability, moisture resistance, and resistance to permanent deformation, although it may lead to a decrease in bulk density and creep rate of modified mixtures. The optimal PE content is recommended to be in the range of 4–12% by weight of binder, yielding substantial improvements in Marshall stability, flow, voids in mineral aggregates (VMA), air voids, dynamic modulus, and overall strength.