Among frequent events in prostate cancer are loss of the tumor-suppressor phosphatase and tensin homologue (PTEN) and overexpression of prostate-specific G-protein-coupled receptor (PSGR), but the potential tumorigenic synergy between these lesions is unknown. Here, we report a new mouse model (PSGR-Pten(Δ/Δ)) combining prostate-specific loss of Pten with probasin promoter-driven PSGR overexpression. By 12 months PSGR-Pten(Δ/Δ) mice developed invasive prostate tumors featuring Akt activation and extensive inflammatory cell infiltration. PSGR-Pten(Δ/Δ) tumors exhibited E-cadherin loss and increased stromal androgen receptor (AR) expression. PSGR overexpression increased LNCaP proliferation, whereas PSGR short hairpin RNA knockdown inhibited proliferation and migration. In conclusion, we demonstrate that PSGR overexpression synergizes with loss of PTEN to accelerate prostate cancer development, and present a novel bigenic mouse model that mimics the human condition, where both PSGR overexpression and loss of PTEN occur concordantly in the majority of advanced prostate cancers, yielding an environment more relevant to studying human prostate cancer.