Abstract Recently, the non-high-density to high-density lipoprotein cholesterol ratio (NHHR) has gained growing attention as an indicator for predicting diseases associated with lipid metabolism. Hepatic steatosis and fibrosis are tightly associated lipid metabolism. Our study aims to analyze the correlations among NHHR, hepatic steatosis, and fibrosis. This study analysed data from 14,578 adults in the US National Health and Nutrition Examination Survey (2005–2018). The degree of hepatic steatosis was measured through the Fatty Liver Index (FLI), while liver fibrosis severity was evaluated with the Fibrosis-4 (FIB-4) index. Multivariate linear regression assessed the association between NHHR and the FLI and FIB-4 score. Smooth curve describing the relationship between NHHR and FLI or FIB-4. Additionally, a two-part linear regression model adopted in order to more accurately account for the nonlinear relationship, with threshold effects estimated through its two components. To confirm the robustness of the findings, interaction tests and subgroup analyses were conducted. The multivariate logistic regression analysis demonstrated a significantly positive correlation of lnNHHR with FLI across all three models. In Model 3, the association was (β = 11.14, 95%CI:10.38,11.90). Curve fitting indicated a nonlinear relationship. The positive correlation between lnNHHR and FLI persists across gender, BMI, and physical activity groups. Nevertheless, a notable negative correlation between lnNHHR and FIB-4 was observed in all three models. In Model 3, the relationship between lnNHHR and FIB-4 was as follows: (β = -0.20; 95% CI: -0.22, -0.17). Curve fitting revealed a V-shaped relationship, with threshold effect analysis identifying a breakpoint at 1.51. Above this threshold, the relationship was found to be statistically insignificant (p-value = 0.424). Receiver operating characteristic (ROC) curve analysis demonstrated that NHHR exhibited better predictive performance for MASLD compared to non-HDL-C, HDL-C, and LDL-C/HDL-C. The current study’s findings suggest that elevated levels of NHHR correlate with a greater risk of hepatic steatosis among adults in the U.S. Our findings imply that NHHR may be a valuable tool in improving MASLD prevention strategies in the general population.