Cardiovascular inflammation has recently emerged as a critical issue across various cardiovascular diseases. Various non-invasive imaging modalities are applied for assessing cardiovascular inflammation. Positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) is a valuable non-invasive imaging tool for identifying active cardiovascular inflammation. It is utilized in evaluating conditions, such as cardiac sarcoidosis, endocarditis, vasculitis, and unstable atherosclerosis. Furthermore, management of cardiovascular complications after aggressive cancer therapy has increasingly been required in cancer patients. FDG PET is considered a suitable approach not only for the assessment of tumor responses to cancer therapy, but also for early and accurate detection of cardiovascular complications. This review highlights the clinical value of FDG PET under appropriate patient preparation. The future perspectives of new molecular imaging tools for assessing active cardiovascular inflammation have been described.