Primary myelofibrosis (PMF) has the least favorable prognosis of the Philadelphia chromosome-negative myeloproliferative neoplasms, which also include essential thrombocythemia (ET) and polycythemia vera (PV). However, clinical presentations and outcomes of PMF vary widely, with median overall survival ranging from years to decades. Given the heterogeneity of PMF, there has been considerable effort to develop discriminatory prognostic models to help with management decisions, particularly for the consideration of hematopoietic stem cell transplantation in patients at higher risk. Although earlier models incorporated only clinical features in risk stratification, contemporary models increasingly use molecular and cytogenetic features, leading to more comprehensive prognostication. This article reviews the most widely adopted prognostic models used for PMF, including the International Prognostic Scoring System (IPSS), dynamic IPSS (DIPSS)/DIPSS+, mutation-enhanced IPSS for transplant-age patients (MIPSS70)/MIPSS70+/MIPSS70+ version 2.0, genetically inspired prognostic scoring system, and Myelofibrosis Secondary to PV and ET-Prognostic Model in patients with post-ET/PV myelofibrosis. We also discuss newly emerging prognostic models and provide a practical approach to risk stratification in patients with PMF and post-ET/PV myelofibrosis.