Aging is the major risk factor for cardiovascular disease, the leading cause of death worldwide. Research on age-related cardiac pathologies has predominantly centered on the left ventricle; however, the atria have been relatively underexplored. This oversight is noteworthy given that atrial dysfunction, including conditions such as atrial fibrillation, plays a significant role in the development of major cardiovascular diseases. In recent years, the aging atrium has drawn increasing clinical interest due to its role in arrhythmogenesis and its association with stroke, heart failure, and thromboembolic events. This review summarizes current knowledge on the cellular and molecular alterations occurring in the aging atria, highlights their clinical implications, and identifies key gaps in understanding that must be addressed to elucidate the mechanisms of atrial dysfunction in the elderly.