Antibiotic pollution in marine ecosystems has emerged as a pressing environmental issue, with potential long-term impacts on marine life and human health. This study presents a comprehensive investigation into the occurrence, distribution, and ecological risks of antibiotics in the East China Sea. Sampling was conducted at 91 sites across five major bays and offshore regions, yielding an extensive dataset on antibiotic pollution in this region. A total of 77 antibiotics were detected, with concentrations ranging from tens to thousands of ng/L. While most sites exhibited relatively low antibiotic concentrations, coastal zones impacted heavily by human activities, such as wastewater discharge and marine aquaculture, showed alarmingly higher levels. These areas (e.g. Taizhou Bay) were identified as pollution hotspots, warranting focused environmental management efforts. Antibiotic concentrations generally decreased from coastal to offshore regions, with distinct shifts in both the composition and ecological risks of detected antibiotics. Sulfonamides were the major antibiotic group in nearshore bays, where their ecological risk was also the highest. In contrast, offshore waters, characterized by lower turbidity, were dominated by macrolides, quinolones, and lincosamides, while sulfonamides, tetracyclines, and β-lactams were found at low levels, likely due to their rapid degradation in these environments. Ecological risk assessments showed that sulfonamides and quinolones posed high risks in polluted nearshore bays, while persistent macrolides, quinolones, and lincosamides exhibited notable concentrations and risks in offshore waters. These findings highlight the need for targeted monitoring and management strategies to address antibiotic pollution effectively in the East China Sea.