Background Sex differences in the trends for control of cardiovascular disease (CVD) risk factors have been described, but temporal trends in the age at which CVD and its risk factors are diagnosed and sex‐specific differences in these trends are unknown. Methods and Results We used the Medical Expenditure Panel Survey 2008 to 2017, a nationally representative sample of the US population. Individuals ≥18 years, with a diagnosis of hypercholesterolemia, hypertension, coronary heart disease, or stroke, and who reported the age when these conditions were diagnosed, were included. We included 100 709 participants (50.2% women), representing 91.9 million US adults with above conditions. For coronary heart disease and hypercholesterolemia, mean age at diagnosis was 1.06 and 0.92 years older for women, compared with men, respectively (both P <0.001). For stroke, mean age at diagnosis for women was 1.20 years younger than men ( P <0.001). The mean age at diagnosis of CVD risk factors became younger over time, with steeper declines among women (annual decrease, hypercholesterolemia [women, 0.31 years; men 0.24 years] and hypertension [women, 0.23 years; men, 0.20 years]; P <0.001). Coronary heart disease was not statistically significant. For stroke, while age at diagnosis decreased by 0.19 years annually for women ( P =0.03), it increased by 0.22 years for men ( P =0.02). Conclusions The trend in decreasing age at diagnosis for CVD and its risk factors in the United States appears to be more pronounced among women. While earlier identification of CVD risk factors may provide opportunity to initiate preventive treatment, younger age at diagnosis of CVD highlights the need for the prevention of CVD earlier in life, and sex‐specific interventions may be needed.