<p>Hot mix asphalt, often known as bitumen, blacktop, or HMA, is the most popular asphalt used in large-scale paving operations. Increasing traffic volume in combination with an insufficient degree of maintenance has caused an accelerated and continuous deterioration of the road networks. In addition, an increase in population with a tremendous growth rate has led to the disposal of a large amount of non-decaying waste materials, which has also become a great concern in developed as well as developing countries. This study presents the partial replacement of fine aggregate by a plastic waste of high-density polyethylene in an asphalt mix with a 19 mm nominal aggregate size. Therefore, in this investigation, Collected and sorted, reduced high-density polyethylene waste (size range from 1 to 5 mm), cleaned, and dried has been introduced randomly to the asphalt mixture at different percentages of high-density polyethylene replacement content (that is, 5, 7, and 9%) by the total weight of asphalt mix. The specimen was put through the Marshall Mix Design process and Refusal Density Design. For a nominal aggregate size of 19 mm, the results show that high-density polyethylene waste can be utilized in asphalt mixtures at the optimum replacement rate of 7%. At the optimum high-density polyethylene plastic replacement stability, flow, bulk density, and voids are within the local and international specifications. In addition, from the refusal density design, it is observed that the modified mix containing 7% high-density polyethylene retains a required minimum air void content after secondary compaction by traffic. For a 19mm nominal aggregate size, based on the economic analysis, asphalt containing 7% high-density polyethylene can save 12.14% costs compared to using a conventional asphalt mix. This research recommends that local authorities confirm the use of high-density polyethylene in asphalt mix with the proposed percentage 7% of the total weight of asphalt mix for improved asphalt mix performance.</p>