PURPOSE: To establish and validate nomograms to predict the overall survival (OS) and cancer-specific survival (CSS) of metaplastic breast cancer(MBC) patients. METHODS: We retrospectively enrolled 948 patients with MBC from the Surveillance, Epidemiology and End Results (SEER) database between 2010 and 2016.Univariate and multivariate Cox analyses were used to determine independent prognostic factors to be included in nomograms for predicting the probabilities of OS and CSS at 1, 2, and 3 years. The concordance index (C-index), receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis were used to check the effectiveness and clinical application of the models. RESULTS: In total, 948 patients were enrolled and randomly assigned to the training (n=664) and validation (n=284) cohorts. Age, tumor size, ethnicity, AJCC stage, radiotherapy, and surgery were identified as independent prognostic factors for OS, while age, tumor size, and AJCC stage were identified as independent prognostic factors for CSS (all p <0.05) and further incorporated into the nomograms. The C-indices for OS and CSS predictions were 0.790 and 0.792 for internal validation and 0.772 and 0.768 for external validation. Both the internal and external validation calibration plots showed excellent agreement between the nomogram predictions and actual survival. ROC curves demonstrated good discriminative ability of the nomograms. CONCLUSION: Nomograms were developed to predict OS and CSS in patients with MBC. These nomograms can help clinicians make more accurate survival assessments and identify patients at high risk of death.