To estimate whether the benefits of aortic aneurysm repair will outweigh the risks, determining individual risks is essential. This single-center prospective cohort study aimed to compare the association of functional tools with postoperative complications in older patients undergoing aortic aneurysm repair. Ninety-eight patients (≥65 years) who underwent aortic aneurysm repair were included. Four functional tools were administered: the Montreal Cognitive Assessment (MoCA); the 4-Meter Walk Test (4-MWT); handgrip strength; and the Groningen Frailty Indicator (GFI). Primary outcome was the association between all tests and 30-day postoperative complications. After adjusting for confounders, the odds ratio for MoCA was 1.39 (95% confidence interval CI 0.450; 3.157; P = 0.723), for 4-MWT 0.63 (95% CI 0.242; 1.650; P = 0.348), for GFI 1.82 (95% CI 0.783; 4.323, P = 0.162), and for weak handgrip strength 4.78 (95% CI 1.338; 17.096, P = 0.016). Weak handgrip strength is significantly associated with the development of postoperative complications after aortic aneurysm repair. This study strengthens the idea that implementing a quick screening tool for risk assessment at the outpatient clinic, such as handgrip strength, identifies patients who may benefit from preoperative enhancement with help from, for example, Comprehensive Geriatric Assessment, eventually leading to better outcomes for this patient group. •Risk stratification in older patients undergoing aortic aneurysm repair is essential.•We compared the association of various functional tools with postoperative complications.•This single-center prospective cohort study included 98 elderly patients.•Weak handgrip strength was significantly associated with postoperative complications.