Increasing evidence supports the important role of necroptosis in podocyte injury during diabetic nephropathy. Ubiquitin-specific peptidase 22 (USP22) is known to be involved in the regulation of necroptosis and high glucose (HG)-induced podocyte injury. This study aimed to indicate whether USP22 contributes to HG-induced podocyte injury via necroptosis. After exposing podocytes to HG for 24, 48, and 72 h, the morphology and viability of podocytes were respectively observed by a microscope and the cell counting kit-8 (CCK-8) assay. Reverse transcription polymerase chain reaction (RT-PCR) was exploited to detect the expression of USP22 in HG-treated podocytes with diverse transfections. Meanwhile, Western blotting was employed to determine the levels of USP22, key molecules of necroptosis (RIPK3 and MLKL), podocyte cell markers (Nephrin and Synaptopodin), and epithelial-mesenchymal transition (EMT)-related proteins (P-cadherin and N-cadherin). The expression of Nephrin was also detected using immunofluorescence. Co-immunoprecipitation (Co-IP) and ubiquitination assays were carried out to explore the mechanism underlying the role of USP22 in necroptosis. The impaired cell viability and the upregulation of USP22, RIPK3, and MLKL were observed in podocytes after HG stimulation. USP22 depletion could restrain HG-induced injury, necroptosis, and EMT in podocytes. Necroptosis inhibitor (necrostatin-1) reversed the decreased cell viability, injury, and EMT induced by USP22 overexpression in HG-treated podocytes. Co-IP assay demonstrated an interaction between USP22 and RIPK3. Furthermore, silencing of USP22 increased the ubiquitination level of RIPK3 in podocytes. Our findings revealed that USP22 inhibition attenuated HG-induced podocyte injury, necroptosis, and EMT by increasing the ubiquitination level of RIPK3.