Bevacizumab, a humanized monoclonal antibody against vascular endothelial growth factor (VEGF), is used in combination with chemotherapy for various malignancies, including metastatic colorectal cancer. While effective, bevacizumab can inhibit normal blood vessel growth, leading to cardiovascular side effects not typically associated with conventional chemotherapy. We report a rare case, from an international perspective, of a 73-year-old man with a history of gastric cancer and newly diagnosed metastatic colorectal cancer complicated by a pre-existing abdominal aortic aneurysm (AAA) measuring 52 mm. The aneurysm was initially managed conservatively, as the multidisciplinary team (MDT) and the patient agreed to prioritize chemotherapy despite the known rupture risk, given his wish to avoid delaying treatment for his cancer. After the diagnosis of colorectal cancer during chemotherapy, bevacizumab was added to his regimen. He developed a rupture of the AAA two days after the fourth dose. Emergent open surgical repair was successfully performed without wound healing complications. This case highlights the potential risk of large-vessel complications associated with bevacizumab, especially in patients with known vascular anomalies. Careful imaging assessment and monitoring are imperative when considering bevacizumab for patients at risk of aortic rupture. In selected cases, prophylactic measures such as preemptive aneurysm repair should be contemplated to optimize safety.