Background <p>Although extensive evidence has identified epidemiological risk factors for comorbidities related to obstructive sleep apnea (OSA), few studies have explored the linear relationship between the atherogenic index of plasma (AIP) and OSA, particularly regarding the mediating role of weight-adjusted-waist index (WWI). This study aimed to elucidate the linear relationship between AIP and OSA symptoms and to quantify the mediating effect of WWI.</p> Methods <p>This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES) 2015–2020, comprising 6,033 participants. To investigate the association between AIP and OSA symptoms, we used multivariable logistic regression, restricted cubic spline models, subgroup analyses, interaction tests, and sensitivity analysis. Additionally, mediation analysis was performed to explore the mediating role of WWI in the AIP-OSA symptoms relationship.</p> Results <p>A positive association between AIP and OSA symptoms was observed. In the fully adjusted model, each 1-unit increase in AIP was associated with a 121% higher risk of OSA. Subgroup analysis revealed that the age interacted with the association, with AIP being associated with increased risk of OSA only in a subgroup of subjects younger than 60 years. Mediation analysis indicated that WWI explained 19.75% of this relationship. Sensitivity analyses using subsamples and a stricter OSA definition confirmed the robustness of these findings.</p> Conclusions <p>The AIP is positively associated with OSA symptoms, and WWI plays a mediating role in this relationship. These findings suggest that monitoring AIP levels and managing WWI may be effective strategies for preventing and reducing the risk of OSA.</p>