Despite improvements in survival rates with maintenance dialysis for end-stage kidney disease (ESKD) patients, malnutrition remains prevalent and closely related to prognosis, suggesting early nutritional assessment is crucial. Thus, this study aimed to validate the modified Nutrition Risk in Critically Ill (mNUTRIC) score as a mortality predictor for incident dialysis patients. This retrospective observational study included 63 dialysis-initiating patients, who were observed for up to 5 years or until death, with survival analyses performed at 6 months, 1 year, and 5 years after dialysis initiation. The modified Nutrition Risk in Critically Ill (mNUTRIC) score was validated for early mortality prediction, with an optimal cut-off value determined. Univariate and multivariate Cox regression analyses were also performed to determine independent predictors of early mortality. Of 63 patients, 19 (30.2%) died within 6 months. The early mortality group was older, had higher acute kidney injury prevalence, lower albumin levels, and higher Acute Physiology and Chronic Health Evaluation Scores (APACHE II), Sequential Organ Failure Assessment (SOFA), and mNUTRIC scores. Receiver operating characteristics (ROC) curve analysis demonstrated that the mNUTRIC score had the highest predictive accuracy (AUC=0.829, p<0.001) with an optimal cutoff value of 5.5, and patients with scores ≥6 had significantly higher mortality rates at all follow-up time points. Multivariate Cox regression analysis validated the mNUTRIC score as the strongest independent predictor of early mortality (HR:1.926, p<0.001). The present study was the first validation of mNUTRIC score in incident dialysis patients. The mNUTRIC score proved to be a valid and robust prognostic tool for predicting both short-term and long-term mortality in patients initiating dialysis. These findings suggest the mNUTRIC score could be a valuable addition to routine clinical assessment protocols due to its objective parameters and ease of application, especially for the growing elderly dialysis population, who are particularly vulnerable to nutritional deficits.