This study aims to identify the optimal Polyethylene Terephthalate (PET) recycling technique in Japan based on multi-criteria decision analysis. Eight environment, eight economy, and five social criteria were shortlisted, scored, and weighted through expert interviews. Mechanical recycling, which extrudes flakes directly into fiber, was the most preferable due to its environmental advantages (with a mean score of 0.86 out of one). Another mechanical recycling technique, which converts flakes into pellets or chips before conversion into fiber, ranked second. Gasification was the least preferred option, with a mean score of 0.57, which was largely due to negative economic effects. Nonetheless, the scoring for gasification was sensitive to changes in the importance given to the environment dimension. Depolymerization may be preferred when economic factors are prioritized. The findings provide insights into potential alternative PET recycling options in the Japanese context based on the systematic assessment of the multifaceted factors influencing the choice of PET recycling technologies. The results also emphasize the importance of selecting recycling alternatives carefully in light of the trend toward increased plastic recycling, and the need for every country to work toward circularity to reduce plastic pollution’s negative impacts by increasing plastic waste recycling.