BACKGROUND AND AIM: Systemic inflammatory markers derived from immune cell counts have been associated with mortality risk in metabolic dysfunction-associated steatotic liver disease (MASLD). However, the clinical relevance of the pan-immune-inflammation value (PIV), a composite index incorporating neutrophil, platelet, monocyte, and lymphocyte counts, in relation to mortality has not been fully elucidated. This study aimed to evaluate the association between PIV and both all-cause and cardiovascular mortality in individuals with MASLD. METHODS: In this population-based cohort study, 15,471 participants with MASLD were identified from the 1999-2018 National Health and Nutrition Examination Survey (NHANES). Baseline demographic characteristics, including age, sex, and ethnicity, were collected. Multivariate Cox proportional hazards models and restricted cubic spline analyses were employed to examine the associations between PIV and mortality outcomes. RESULTS: In fully adjusted models, log-transformed PIV (LnPIV) was independently associated with higher risks of all-cause (hazard ratio [HR] 1.26; 95% confidence interval [CI], 1.14-1.38) and cardiovascular mortality (HR 1.31; 95% CI, 1.10-1.56). Notably, a U-shaped nonlinear association was observed between PIV and all-cause mortality, while a J-shaped relationship was found for cardiovascular mortality. These associations were more pronounced among individuals with a poverty-income ratio (PIR) < 1, suggesting increased vulnerability in socioeconomically disadvantaged populations. CONCLUSION: PIV may be a biomarker associated with increased mortality risk in individuals with MASLD, particularly among those from lower socioeconomic backgrounds. These findings underscore the association between PIV and mortality risk and highlight the need for further prospective validation to evaluate its potential role in risk stratification.