Plastic pollution threatens marine ecosystems, but research on interactions between plastic and marine fauna, especially entanglement at the national level is limited. This study aims to address this deficit by investigating marine fauna entanglement with marine debris in South Korean coastal and marine ecosystems. Comprehensive data were collected from government wildlife rescue centers, an online platform, internet searches, and scuba divers' underwater exploration descriptions. A total of 428 entanglement cases were documented (338 from coastal areas and 90 from underwater exploration) between 2003 and 2023. The analysis identified at least 77 affected species, including birds, sea turtles, marine mammals, fish, corals, and marine invertebrates. Overall, 13.0 % were listed as threatened or near threatened by the International Union for Conservation of Nature (IUCN) Global Red List, and 14.5 % were legally protected in Korea. The total number of entanglements considerably increased over time, especially in coastal regions. The sources of entanglement primarily involve monofilament lines and hooks associated with recreational fishing, as well as other fishing-related debris such as nets, ropes, and traps. These entanglements affect multiple groups of animals across different taxa. Our results support the need for stricter regulations and improved management of fishing activities to mitigate their impact on marine life. Future efforts should focus on enhancing data collection methods and integrating contributions from government agencies, associated organizations, and citizen scientists. Citizen scientist involvement will be particularly valuable for collecting data in less accessible underwater areas. Our findings may also apply to other large marine ecosystems with similar data deficits.