Background <p>Currently, the optimal adiposity indices for diagnosing and predicting the prognosis of atherosclerotic cardiovascular disease (ASCVD) remain undefined. The purpose of this study is to compare the associations between ten traditional or novel adiposity indices and ASCVD in a large population sample.</p> Methods <p>A total of 13,933 participants from 10.6 NHANES cycles, spanning from 1999 to 2020, were included. The associations between 10 traditional and novel adiposity indices, including A Body Shape Index (ABSI), Body Fat Percentage (BFP), Body Mass Index (BMI), Body Roundness Index (BRI), Conicity Index (C-index), Lipid Accumulation Product (LAP), Relative Fat Mass (RFM), Visceral Adiposity Index (VAI), Waist-to-Height Ratio (WHtR), and Weight-adjusted Waist Index (WWI), and ASCVD were analyzed.</p> Results <p>Among the 13,933 participants included, 1133 were identified with ASCVD. First, in logistic regression and restricted cubic spline (RCS) analyses, ABSI, BFP, BMI, BRI, C-index, RFM, WHtR, and WWI were all independently and linearly positively associated with CHF, while LAP and VAI showed no significant association with ASCVD. In receiver operating characteristic curve (ROC) analysis, ABSI demonstrated the best performance in diagnosing ASCVD [area under curve (AUC) = 0.714]. Second, in Cox regression, ABSI and BMI were found to increase and decrease the risk of cardiovascular disease (CVD) mortality in ASCVD patients, respectively. In time-dependent ROC analysis, ABSI remained the optimal predictor for CVD mortality risk in ASCVD patients, with AUC values of 0.7, 0.65, and 0.63 for 5-year, 10-year, and 15-year predictions, respectively.</p> Conclusion <p>ABSI was found to increase the odds of ASCVD incidence and the risk of poor prognosis. Moreover, ABSI demonstrated superior performance in both the diagnosis and prognosis of ASCVD compared to other indices.</p>