Understanding the distribution of seagrass meadows is the first critical step toward their effective conservation and management. This study provides the first comprehensive assessment of Zostera species distribution along the southeastern coast of Korea’s South Sea. The survey encompassed coastal areas from Haeundae in Busan to Changwon, Geoje, Tongyeong, Sacheon, Goseong, Namhae, and Hadong in Gyeongsangnam-do, using local fisheries cooperative questionnaires, boat-based snorkeling, and SCUBA diving. Four Zostera species were identified: Zostera marina, Z. caespitosa, Z. caulescens, and Z. japonica. Among the 162 surveyed sites, Z. marina was the most prevalent, occurring at 140 sites (86.4%), followed by Z. japonica (10 sites, 6.2%), Z. caespitosa (9 sites, 5.6%), and Z. caulescens (3 sites, 1.9%). The total seagrass coverage by Zostera species in the region was 1,174.2 hectares, with species-specific coverage as follows: Z. marina (798.7 ha, 68.0%), Z. japonica (339.4 ha, 28.9%), Z. caulescens (29.0 ha, 2.5%), and Z. caespitosa (7.1 ha, 0.6%). The mean occurrence depths were 2.0±0.1 m for Z. marina and 2.7±0.2 m for Z. caespitosa, with the latter found slightly deeper. Z. caulescens occurred at the greatest depths, averaging 6.8±0.5 m (range: 5.0~8.8 m), while Z. japonica was limited to the intertidal zone. Z. marina predominated in all regions except Busan, while the Nakdong River estuary contained the nation’s largest Z. japonica habitat. Z. caespitosa was observed in Geoje, Changwon, and Tongyeong, whereas Z. caulescens was restricted to Geoje. These findings provide essential baseline data for the conservation and management of Zostera species in Korean coastal waters.