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STUDY DESIGN Retrospective analysis. OBJECTIVE This study aimed to establish nomograms for predicting overall survival (OS) and cancer-specific survival (CSS) in patients with solitary plasmacytoma of the spine (SPS). SUMMARY OF BACKGROUND DATA SPS is a rare type of malignant spinal tumor. A systematic study of prognostic factors associated with survival can provide guidance to clinicians and patients. Consideration of other causes of death (OCOD) in CSS will improve clinical practicability. METHODS A total of 1,078 patients extracted from the SEER database between 2000 and 2018 were analyzed. Patients were grouped into training and testing datasets (7:3). Factors associated with OS and CSS were identified by Cox regression and competing risk regression, respectively, for the establishment of nomograms on a training dataset. The testing dataset was used for external validation of the performance of the nomograms using calibration curves, Brier's scores, C-indexes, time-dependent receiver operating characteristic (ROC) curves, and decision curve analysis (DCA). RESULTS Age and grade were identified as factors associated with both OS and CSS, along with marital status, radiation for OS and chemotherapy for CSS. Heart disease, cerebrovascular disease, and diabetes mellitus were found to be the three most common causes of OCOD. The nomograms showed satisfactory agreement on calibration plots for both training and testing datasets. Integrated Brier score, C-index, and overall area under the curve (AUC) on the testing dataset were 0.162/0.717/0.789 and 0.173/0.709/0.756 for OS and CSS, respectively. DCA curves showed a good clinical net benefit. Nomogram-based web tools were developed for clinical application. CONCLUSION This study provides evidence for risk factors and prognostication of survival in SPS patients. The novel nomograms and web-based tools we developed demonstrated good performance and might serve as accessory tools for clinical decision-making and SPS management. LEVEL OF EVIDENCE 3.