Purpose <p>To examine the relationship between biological aging and the prevalence of NAFLD.</p> Method <p>We used the recommended sampling weights to account for the complex survey design of NHANES. The analysis, utilizing data from 2005 to 2016, aimed to investigate the impact of biological aging on NAFLD prevalence using various statistical methods. A restricted cubic spline (RCS) model was applied to explore the dose-response relationship, while logistic regression examined linear associations. The robustness of the association across different subgroups was also tested.</p> Result <p>The study included 2786 participants. We found significant associations between NAFLD and the following biological aging metrics: AL score (OR (95%CI) = 1.1932 (1.0597 ~ 1.3435), <i>P</i> = 0.0035), HD (OR (95%CI) = 1.2092 (1.0565 ~ 1.3839), <i>P</i> = 0.0058), and PA (OR (95%CI) = 1.7564 (1.1949 ~ 2.5818), <i>P</i> = 0.0042). All biological aging metrics were identified as independent predictors. PA was most associated with the prevalence of NAFLD. The associations persisted across most subgroups.</p> Conclusion <p>The prevalence of NAFLD was associated with biological aging, emphasizing the importance of addressing potential health risks related to aging.</p>