INTRODUCTION:: In metabolic dysfunction–associated steatotic liver disease, the diagnostic efficacy of controlled attenuation parameter (CAP) was not very accurate in evaluating liver fat content. The aim of this study was to develop a score, based on CAP and conventional clinical parameters, to improve the diagnostic performance of CAP regarding liver fat content. METHODS:: A total of 373 participants from 2 independent Chinese cohorts were included and divided into derivation (n = 191), internal validation (n = 75), and external validation (n = 107) cohorts. Based on the significant difference index between the 2 groups defined by the magnetic resonance imaging–proton density fat fraction (MRI-PDFF) in derivation cohort, the optimal model (CAP-BMI-AST score [CBST]) was screened by the number of parameters and the area under the receiver operating characteristic curve (AUROC). In the internal and external validation cohorts, the AUROC and corresponding 95% confidence intervals (CIs) were used to compare the diagnostic performance of CBST with that of CAP. RESULTS:: We constructed the CBST = −14.27962 + 0.05431 × CAP − 0.14266 × body mass index + 0.01715 × aspartate aminotransferase. When MRI-PDFF was ≥20%, ≥10%, and ≥5%, the AUROC for CBST was 0.77 (95% CI 0.70–0.83), 0.89 (95% CI 0.83–0.94), and 0.93 (95% CI 0.88–0.98), which was higher than that for CAP respectively. In the internal validation cohort, the AUROC for CBST was 0.80 (95% CI 0.70–0.90), 0.95 (95% CI 0.91–1.00), and 0.98 (95% CI 0.94–1.00). The optimal thresholds of CBST were −0.5345, −1.7404, and −1.9959 for detecting MRI-PDFF ≥20%, ≥10%, and ≥5%, respectively. DISCUSSION:: The CBST score can accurately evaluate liver steatosis and is superior to the CAP.