Asphalt mixtures are widely used in the construction of flexible pavements due to their cost-effectiveness and ease of construction. However, their mechanical performance can deteriorate under conditions such as heavy traffic loads, temperature variations, and moisture exposure. To enhance performance, this study investigates the effect of polyethylene modification on the mechanical properties of asphalt. Reclaimed polyethylene, sourced from locally available milk packaging (OMFED), was used as a polymer additive in three types of asphalt mixes: Bituminous Concrete (BC), Dense Bituminous Macadam (DBM), and Stone Mastic Asphalt (SMA). The study determined the Optimum Binder Content (OBC) and Optimum Polyethylene Content (OPC) for each mix using the Marshall method. The OBC for mixes with stone dust filler was 4%, while the use of granulated blast furnace slag and fly ash as fillers resulted in OBCs of 5% for SMA and 4% for BC and DBM. The OPC was found to be 2% for SMA and DBM, and 1.5% for BC when using stone dust; for mixes with slag and fly ash, the OPC was 1.5% across all types. Performance evaluation through drain down tests, static indirect tensile strength tests, and static creep tests revealed that the inclusion of polyethylene significantly improves key mechanical properties of the asphalt mixes. The modified mixes showed enhanced Marshall Stability, reduced binder drain down, and better resistance to deformation and cracking, indicating that polyethylene is an effective stabilizing additive in asphalt pavements.