<p>As widely invasive organisms, ascidians have caused significant economic and ecological damage globally. While significant progress has been made in documenting ascidian invasions globally in recent years, there remains a lack of systematic assessments that comprehensively integrate anthropogenic and biological factors, considering the profound and well-documented link between ascidian invasions and human activities. This study established an ascidian invasion risk assessment system. Firstly, we employed the optimized species distribution models to project the distribution patterns and changes of habitat for three typical invasive ascidian species (<i>Ciona robusta</i>, <i>C</i>. <i>savignyi</i>, and <i>Styela clava</i>), and conducted an in-depth analysis of their ecological niches. The results showed that <i>C. robusta</i> and <i>C. savignyi</i> exhibited a high degree of overlap in their distribution areas and ecological niches. Environmental response curves indicated that the overlap was caused by key environmental factors such as temperature and chlorophyll levels. Comparative analysis revealed that the three species have significantly different temperature tolerance ranges, particularly in terms of cold tolerance. Secondly, we adopted an optimized objective weighting method that integrated anthropogenic, biological, and environmental factors. Based on these findings, we conducted a graded assessment of global invasion risks and provided corresponding policy recommendations. This study not only yields valuable insights into understanding the mechanism of ascidian invasions, but also provides a reference for fisheries practices and management.</p>