Numerous studies have emphasized the importance of the ubiquitin-proteasome system (UPS) in the malignant progression of ovarian cancer (OC). However, whether ubiquitination-related genes (UbRGs) can be used to predict the prognosis of OC remains to be revealed. Patients with OC were divided into two clusters based on the expression of UbRGs, and prognosis was compared between the two clusters. A prognostic model was established based on UbRGs, and its predictive efficiency was validated using Kaplan-Meier (K-M) curves, receiver operating characteristic (ROC) curves, and a nomogram. Immune infiltration and gene mutation analyses were used to examine the effects of UbRGs on the prognosis of OC. The prognostic model served as a valid and independent predictor of OC prognosis. Immune infiltration revealed that the unique immune microenvironment of OC was regulated by UbRGs. Gene mutation analysis indicates that UbRGs likely influence OC malignant behavior by modulating gene mutation patterns. In addition, Ube2j1 was found to play an important role in regulating the malignant progression of OC. Furthermore, the mechanism by which Ube2j1 modulates the OC phenotype and reshapes its immune microenvironment via the JAK2/STAT3/PD-L1 pathway was elucidated, providing novel insights into the potential for ubiquitination-based immunotherapy in OC. This study provides novel insights into precision immunotherapy based on UbRGs in OC. The UbRGs-based prognostic model may help to provide novel insights for the application of ubiquitination-based immunotherapy in OC.