Age-related declines in cardiac function and exercise tolerance interfere with healthy living and decrease healthy life expectancy in older individuals. Tamogi-take mushrooms (Pleurotus cornucopiae) are known to contain high levels of Ergothioneine (EGT), an antioxidant with potential health benefits. In this study, we assessed the possibility that long-term consumption of Tamogi-take mushrooms might attenuate age-related decline in cardiac and vascular endothelial function in mice. We found that long-term intake of Tamogi-take mushrooms significantly maintained cardiac and vascular endothelial function and improved exercise tolerance in mice. Long-term mushroom consumption also increased levels of Nrf2 (Nuclear factor E2-related factor 2) protein in heart tissues and increased translation of HO-1 (Heme Oxygenase 1) proteins, which have antioxidant effects in heart and aortic tissues. Finally, long-term Tamogi-take mushroom consumption inhibited ROS accumulation with aging and reduced expression of inflammatory biomarkers. We conclude that ingestion of Tamogi-take mushrooms could serve as a dietary intervention to promote cardiovascular health, support healthy aging and slow the progression of age-related diseases.