Coronary artery involvement in giant cell arteritis (GCA) is rare but can lead to severe complications, including myocardial infarction and death. We present unique 2-[18F]fluorodeoxyglucose positron emission tomography/computed tomography (2-[18F]FDG-PET/CT) findings in a 91-year-old woman with GCA. In addition to typical aortic and supra-aortic involvement, this scan revealed intense FDG uptake in the coronary arteries, including the left main trunk, left anterior descending, circumflex, and right coronary arteries. This inflammatory pattern was consistent with GCA, with no signs of atherosclerosis on coronary CT angiography. Early identification of coronary inflammation enabled timely immunosuppressive therapy, potentially preventing fatal outcomes.