Aims: To establish a nomogram-scoring model for evaluating the risk of death in patients with critical cardiovascular disease after continuous renal replacement therapy (CRRT) in a coronary care unit (CCU). Methods: This retrospective cohort study included data collected on 172 patients, in whom CRRT was initiated in the CCU between January 2017 and June 2021. Predictors of mortality were selected using an adaptive least absolute shrinkage and selection operator logistic model and used to construct a nomogram. The nomogram was evaluated using the concordance index (C-index) and Hosmer–Lemeshow test. Results: The number of patients who died in-hospital after CRRT was 91 (52.9%). The results of the multivariate logistic regression analyses clarified that age, history of hypertension and/or coronary artery bypass grafting, a diagnosis of unstable angina pectoris or acute myocardial infarction, ejection fraction, systolic blood pressure, creatinine, neutrophil, and platelet counts before CRRT initiation were significant predictors of early mortality in patients treated with CRRT. The nomogram constructed on these predictors demonstrated significant discriminative power with an unadjusted C-index of 0.902 (95% CI: 0.858–0.945) and a bootstrap-corrected C-index of 0.875. Visual inspection showed a good agreement between actual and predicted probabilities (Hosmer–Lemeshow \chi{}^2 = 5.032, p-value = 0.754). Conclusions: Our nomogram based on nine readily available predictors is a reliable and convenient tool for identifying critical patients undergoing CRRT at risk of mortality in the CCU.