This study focuses on the development of a sustainable and cost-effective road construction process with the use of Reclaimed Asphalt Pavement (RAP), warm mix additives (WMA), and Waste Cooking Oil (WCO) in Stone Matrix Asphalt (SMA). RAP was used in varying proportions (20–40%), Sasobit (WMA additive) in 2–5%, and WCO as a softening agent. Series of laboratory tests such as SARA fractions, Marshall properties, moisture susceptibility, resilient modulus, and rutting resistance were carried out to evaluate the mechanical and performance characteristics. A multivariate analysis approach was employed to rank these mixes based on their performance parameters and to determine the best-performing mix. Among all the mix combinations, the mix containing 30% RAP, 3% Sasobit, and 6% WCO (referred as WS30R) in Polymer Modified Bitumen (PMB) demonstrated the best performance. Compared to conventional SMA mix (3WS), the WS30R mix improved rutting resistance by 41%, resilient modulus by 15%, and moisture resistance. The findings confirm that inclusion of RAP, WMA, and WCO enhances the performance of SMA while promoting sustainability. This synergetic improvement provides a practical and eco-friendly solution for modern road construction through the use of sustainable materials.