Cyclin-dependent kinase subunit (CKS) 2 is a member of the CKS family, which plays an important role in the regulation of meiosis and mitosis. Overexpression of CKS2 has been reported in several types of tumors. However, few studies have investigated its role in uterine leiomyosarcoma (ULMS). In the present study, the expression of CKS2 in 38 cases of ULMS and 38 cases of uterine leiomyoma (ULM) was analyzed by immunohistochemistry. Moreover, the functional analysis of CKS2 was performed in ULMS cell lines. A significantly higher expression of CKS2 was found in ULMS tissues than in ULM tissues (P<0.01) and high CKS2 expression was associated with increased tumor size, low progesterone receptor expression and poor prognosis in patients with ULMS. Multivariate Cox regression analysis revealed that CKS2 expression status was an independent predictor of overall survival for ULMS. Furthermore, silencing of CKS2 in ULMS cells inhibited cell proliferation, colony formation, migration and invasion, and resulted in cell cycle arrest. In conclusion, the present study demonstrated that CKS2 may serve as a marker for the differential diagnosis of ULMS and ULM. In addition, it may act as an independent prognostic factor in patients with ULMS, and serve as a novel target for ULMS therapy.