Classical BCR-ABL-negative myeloproliferative neoplasms are a heterogeneous group of hematologic malignancies, including essential thrombocythemia, polycythemia vera, and primary myelofibrosis. Monocytes, immune cells derived from hematopoietic stem cells, exhibit significant heterogeneity and contribute to immune regulation through cytokine secretion and differentiation into dendritic cells and macrophages. Aberrant monocytes are associated with the prognosis of MPNs, particularly PMF. Furthermore, these altered monocytes play a critical role in the pathogenesis and progression of MPNs. This review aims to explore the heterogeneity of different monocyte subsets during homeostasis and focuses on the potential mechanisms by which monocytes contribute to the development and progression of MPNs.