We have previously shown that consumption of a western diet (WD) high in fat and sugars induces obesity, insulin resistance, cardiac diastolic dysfunction and vascular endothelial dysfunction. These deleterious effects of WD‐consumption appear earlier and are greater in female than in male mice. We hypothesize that the WD‐induced endothelial dysfunction is caused in part by overexpression and increased activity of epithelial Na channels (ENaC) in the vascular endothelium, that the endothelial cell (EC) ENaC overexpression is driven by an augmented EC mineralocorticoid receptor (MR) activity, and that the increased ENaC activity in the endothelium would be associated with increased EC stiffness and reduced flow‐induced dilatory capacity. To test these hypotheses, 4‐week old ECMR+/+ and ECMR−/− female mice were fed a WD (46% fat, 17.5% sucrose, 17.5% high‐fructose corn syrup) for 16 weeks. At 20 weeks of age mice were sacrificed and their aortae and mesenteric resistance arteries excised for ex vivo analyses. Aortic endothelial ENaC content was greater (P<0.05) and the aortic endothelium was stiffer (P<0.05) in ECMR+/+ than ECMR−/− mice as determined by immunohistochemistry and atomic force microscopy, respectively. Ex vivo exposure to the ENaC inhibitor, Amiloride (1mM), reduced endothelial stiffness in aortae. Accordingly, flow‐induced vasodilatory responses were greater (P<0.05) in mesenteric resistance arteries from ECMR−/− than in those from ECMR+/+ and Amiloride (1mM) improved flow‐induced dilations only in arteries from ECMR+/+ mice. These results suggest that endothelial dysfunction in WD‐fed female mice is associated with vascular endothelial stiffness resulting from endothelial MR‐dependent overexpression and increased activity of ENaC in the vascular endothelium. Moreover, our results indicate that ENaC inhibition with Amiloride may represent a novel strategy to prevent and treat the endothelial dysfunction associated with consumption of a WD in females.