This study aimed to comprehensively analyze the effects of the COVID-19 pandemic on the corporate sustainability performance of Turkish Airlines (THY). The aviation sector was one of the sectors most severely affected during the pandemic. In the study, THY's annual sustainability reports and other official data published in the relevant period were analyzed. 17 indicators were employed for economic sustainability, 15 for environmental sustainability and 25 for social sustainability. Performance evaluation was carried out using multi-criteria decision making (MCDM) methods. First, the criterion weights were determined using the Entropy method. Subsequently, the EDAS (Evaluative Distance from Average Solution) ranking technique was applied to rank THY's sustainability performance on an annual basis. The findings indicate that the COVID-19 pandemic has multi-dimensional effects on THY's corporate sustainability performance. Despite the improvement in economic sustainability, there was a significant decline in environmental sustainability and fluctuations were observed in social sustainability. These results suggest that THY should review its sustainability strategies and develop longer-term policies, especially in the field of environmental sustainability. In addition, strategic steps should be taken in the domain of social sustainability as well to minimize the effects of the pandemic and create a more resilient structure when faced with similar situations in the future.