Background <p>The relationship between the gut microbiome and metabolic dysfunction-associated fatty liver disease (MAFLD) has garnered increasing attention. However, the association between the dietary index for gut microbiota (DI-GM), a measure of microbiome diversity, and MAFLD has yet to be fully explored.</p> Methods <p>Data from the 2017–2020 National Health and Nutrition Examination Survey (NHANES) were analyzed, including 7243 participants. The association between DI-GM and MAFLD was investigated using weighted logistic regression, restricted cubic spline (RCS), and subgroup analyses.</p> Results <p>A notable inverse association was identified between DI-GM and the prevalence of MAFLD, with each 1-point increase in DI-GM corresponding to a 6.1% reduction in MAFLD prevalence (OR = 0.939, 95% CI: 0.901–0.980). Individuals with a DI-GM score of 6 or higher had an adjusted OR of 0.794 (95% CI: 0.665–0.947) compared to those with a DI-GM score of 0–3. RCS analysis further revealed a linear relationship between DI-GM and MAFLD risk. Additionally, subgroup analyses suggested that race may modify the association between DI-GM and MAFLD (P for interaction &lt; 0.05).</p> Conclusions <p>DI-GM is inversely associated with MAFLD prevalence, and race appears to be a significant modifier of this relationship.</p>