The histone demethylase KDM6A controls gene expression by the epigenetic regulation of H3K27 methylation and functions in diverse processes, including differentiation, development, and cancer. Here, we investigated the role of KDM6A in prostate cancer (PCa). Specific homozygous deletion of KDM6A in the adult mouse prostate epithelium strongly inhibited tumor progression initiated by the homozygous loss of PTEN. Mechanistically, KDM6A promoted prostate tumorigenesis and lipid metabolism by binding to the SREBP1c promoter to increase SREBP1c transcription. USP7 deubiquitinated KDM6A to increase its expression. KDM6A was significantly up-regulated in PCa and positively associated with USP7 expression. Furthermore, targeting KDM6A stability by inhibiting USP7 in conditional knockout mice and xenograft models markedly suppressed PCa growth and significantly enhanced KDM6A inhibitor efficacy. Collectively, these findings indicate that KDM6A regulates prostate lipid metabolism and is essential for prostate tumorigenesis initiated by PTEN loss. Targeting USP7/KDM6A could be a valuable strategy to ameliorate prostate cancer progression and therapeutic resistance.