This study involves a material flow analysis (MFA) of single-use plastics (SUPs) and packaging materials in the Republic of Korea, focusing on their short lifespans and significant contributions to plastic waste. Based on the MFA results, recommended policies for managing packaging materials and SUPs were proposed. In 2021, 6.340 Mt of synthetic resin were produced, with 39.7% (2.518 Mt) utilized for packaging materials and SUPs. The per capita consumption of these materials was 48.7 kg/year, surpassing global averages. The separate collection rate was 54.6%, with films (26.2%) and manufacturing facilities (10.6%) exhibiting the lowest rates. The overall recycling rate was 52.7%, and 981 t of recycled waste was directly placed in soil. The reliability of the MFA results was estimated to be 83.1%, which is an improvement compared to previous studies. Recommendations include reducing plastic use, expanding recycling infrastructure, raising public awareness, and implementing stricter regulations to control soil contamination.