BACKGROUND: The triglyceride glucose index (TyG index) is a crucial marker for assessing the risk of chronic diseases, while socioeconomic status (SES), measured by poverty income ratio (PIR) and education level, reflects an individual's social standing. Past studies have linked SES to diabetes and cardiovascular diseases, but research on its association with the TyG index is limited. This study aimed to explore the association between SES and the TyG index and assess the mediating role of BMI. METHODS: The cross-sectional study utilized data from the National Health and Nutrition Examination Survey 2007-2016 cycles to explore the relationship between SES and the TyG index in the adult of the USA. Multivariate logistic regression, stratified and interaction analyses were conducted to assess the association between SES and the TyG index. Additionally, parallel mediator analysis estimated the mediated effect of BMI between SES and the TyG index. RESULTS: Among the 11,358 individuals studied, averaging 49 years of age and with 48.3% males, fully adjusted models revealed negative associations between PIR and education level with the TyG index, while BMI showed a positive correlation. Stratified and interaction analysis indicated consistent findings across subgroups. Mediation analysis revealed that BMI mediated 14.4% and 8.57% of the effects of PIR/Education level on the TyG index, respectively. CONCLUSIONS: SES was negatively associated with the TyG index. Additionally, BMI partially mediate the association between SES and the TyG index. These findings deepen the comprehension of the association between SES and the TyG index.