Background: Adipose insulin resistance (Adipo-IR) is associated with multiple metabolic diseases, including non-alcoholic fatty liver disease (NAFLD). The study aimed to evaluate sex differences in the association between Adipo-IR and NAFLD, and further investigated other potential modifiers. Methods: This cross-sectional study enrolled adults without diabetes who underwent physical examinations in Beijing Chao-Yang Hospital. We calculated the Adipo-IR index as the product of the fasting insulin and free fatty acid concentration. We categorized Adipo-IR into four groups according to quartiles, using the first interquartile range (Q1) as the reference. Logistic regression was used stratified by the modifiers after adjustment for potential confounders. Results: There were 5586 participants in the study, 49.8% (n = 2781) of whom were women and 30.4% (n = 1698) with NAFLD. There was a graded positive association between Adipo-IR and NAFLD, with sex (P = 0.01) and hyperlipidemia (P = 0.02) modifying this association. In the hyperlipidemic women, for one unit increase in log-Adipo-IR, the odds of having NAFLD increased by 385% after adjustment for potential confounders (OR = 4.85, 95%CI 3.54–6.73, P < 0.001). However, it turned out that the odds of having NAFLD increased by 131% (OR = 2.31, 95%CI 1.74–3.11, P < 0.001), 216% (OR = 3.16, 95%CI 2.56–3.93, P < 0.001), 181% (OR = 2.81, 95%CI 1.88–4.28, P < 0.001) in normolipidemic men, hyperlipidemic men, and normolipidemic women, respectively. Similarly, the ORs for the association between Adipo-IR and NAFLD in women with age ≥ 50 years were higher than ORs in women with age < 50 years. Conclusions: The positive correlation between Adipo-IR and NAFLD was stronger in hyperlipidemic women, compared with normolipidemic or hyperlipidemic men, or normolipidemic women. The association also strengthened for women over 50 years. Treatment strategies targeting Adipo-IR to alleviate NAFLD may be of value, especially in hyperlipidemic women after menopause. Plain language summary: In our study, we focused on non-alcoholic fatty liver disease (NAFLD), a condition characterized by excessive fat in the liver not caused by alcohol use. NAFLD is often connected to problems with how our body uses insulin, a hormone that helps regulate sugar levels. Adipose insulin resistance (Adipo-IR), or the inability of adipose cells to respond properly to insulin, can lead to more fat getting stored in the liver, worsening NAFLD. Previous research has indicated that NAFLD risk factors and outcomes can vary between sexes. For example, men are generally more susceptible to NAFLD during their reproductive years, whereas postmenopausal women have a risk level similar to or even exceeding that of men. We were particularly interested in how Adipo-IR affects the risk and progression of NAFLD differently in men and women. We conducted a large-scale study involving over 5,000 Chinese adults without diabetes. Our findings reveal a stronger association between Adipo-IR and NAFLD in women, especially in those with high lipid levels in their blood or who are over 50 years. This implies that treatments targeting Adipo-IR, such as weight loss strategies and certain medications, such as thiazolidinediones, might be particularly effective for these groups of women. Given the rising global prevalence of NAFLD, our research offers valuable insights for tailoring treatment strategies and could help identify which populations would benefit most from targeted interventions to mitigate the disease. Highlights: Adipo-IR is positively correlated with NAFLD in subjects without diabetes. The positive association between Adipo-IR and NAFLD is sex-specific, and it strengthened for hyperlipidemic women. Among all the lipid indicators, low-density lipoprotein cholesterol acted as the main modifier. The association also strengthened for women over 50 years compared with women less than 50 years. [ABSTRACT FROM AUTHOR]