Background/Objectives: Abdominal aortic aneurysm (AAA) repair is a prophylactic intervention aimed at preventing rupture. As the population ages, surgical decision-making becomes increasingly complex, especially in older and frailer patients. Imaging biomarkers, such as psoas muscle area (PMA) and density (PMD), have been proposed as surrogates for frailty and potential predictors of surgical outcomes. However, their clinical utility remains uncertain. Methods: In this retrospective, single-center study, we evaluated 199 patients who underwent elective AAA repair between 2015 and 2019. Preoperative computed tomography angiography (CTA) was used to measure PMA and PMD at the level of the third lumbar vertebra. Lean psoas muscle area (LPMA) was calculated as the product of PMA and PMD. Sarcopenia was defined as the lowest tertile of each measurement. Outcomes were assessed using Fisher’s exact test, Kaplan–Meier survival analysis, and logistic regression. Results: No significant associations were found between PMA, PMD, or LPMA and early or late postoperative complications or mortality. Conclusions: Psoas muscle indices, measured on routine CTA scans, do not reliably predict postoperative outcomes in AAA patients. These findings suggest that further studies integrating broader clinical and functional assessments are needed to improve risk stratification and inform preoperative decision-making in this patient population.