Objectives: Image-based sarcopenia has been the subject of recent studies, hypothesized as a prognostic factor for patients with thoracoabdominal aortic aneurysms. Methods and Materials: We conducted a single-center retrospective analysis of patients who underwent complex endovascular repair for thoracoabdominal aortic aneurysms between 2008 and 2016. CT image assessment was performed and patients were classified as sarcopenic and non-sarcopenic using two stratification methods: skeletal mass index (SMI) and total psoas muscle index (TPMI). According to sex, each patient was defined as sarcopenic if their SMI or TPMI was in the lowest third of the study group. The primary endpoint was impact of sarcopenia on perioperative mortality and long-term survival. Secondary endpoints were perioperative complications. Results: From a total of 155 patients, 135 were eligible for study. Overall, in-hospital mortality was 5.9% (8/135). The 30-day, 1-year, 3-year and 5-year mortality was 10.4% (14/135), 20% (27/135), 28.1% (38/135) and 31.1% (42/135), respectively. There was no difference in the long-term mortality rates between sarcopenic and non-sarcopenic patients regardless of the stratification method used (p = 0.4 for SMI and p = 0.2 for TPMI). According to SMI, 30-day mortality of sarcopenic patients was significantly lower in comparison to non-sarcopenic patients (1/45, 2.2% vs. 13/90, 14.4%, p = 0.028). Based on the total psoas muscle index, sarcopenic patients were at higher risk for development of pulmonary complications in comparison to non-sarcopenic patients postoperatively (p = 0.03). Conclusion: Using SMI and TPMI, sarcopenia was not associated with reduced long-term survival in patients undergoing complex endovascular repair for thoracoabdominal aortic aneurysms.