Purpose <p>Reproductive lifespan was defined as the number of years between menarche and menopause, which is an important indicator for assessing female reproductive health. Dietary nutrient intake may have a significant impact on estrogen levels and reproductive capacity in women. However, the evidence for the correlation between dietary flavonoid intake and reproductive lifespan is unclear. Our study aimed to explore the relevance of dietary flavonoid intake and reproductive lifespan.</p> Methods <p>Our research was based on a sample of 622 naturally menopausal females who participated in the 2007–2008, 2009–2010, and 2017–2018 National Health and Nutrition Examination Surveys (NHANES). We collected data on flavonoid intake using a 24-hour dietary intake assessment model and evaluated reproductive lifespan by surveying participants’ ages at menarche and menopause. We used a linear regression model to explore the link between total flavonoids intake and reproductive lifespan, and a categorical logistic regression model was used to examine the relevance of dietary flavonoid subclasses intake and reproductive lifespan. The restricted cubic spline (RCS) was employed to evaluate the potential nonlinear relationship.</p> Results <p>After adjusting for covariates, we discovered a potential linear positive correlation between total flavonoids intake and reproductive lifespan. Our multivariate logistic regression model showed that moderate elevations in anthocyanidins and flavan-3-ols intake were linked to extended reproductive lifespan. Furthermore, our findings suggest a possible non-linear positive association between flavones and flavonols intake and reproductive lifespan (<i>p</i>-value for non-linearity &lt; 0.05).</p> Conclusion <p>Our study suggested that an appropriate increase in dietary flavonoids intake may prolong female reproductive lifespan and promote reproductive health.</p>