This systematic review and meta-analysis evaluates the efficacy and safety of PARP inhibitors (PARPi) in treating advanced ovarian cancer. The study included all phase II and III randomized controlled trials (RCTs) assessing PARPi from inception to April 13, 2022. The main outcomes were progression-free survival (PFS), overall survival (OS), and adverse events (AEs). **Results:** - **PFS:** In recurrent ovarian cancer, PARPi maintenance therapy significantly improved PFS over placebo in the total population (HR 0.34, CI 0.29–0.40), BRCA mutant (HR 0.24, CI 0.18–0.31), germline BRCA mutant (HR 0.23, CI 0.18–0.30), and BRCA wild-type cases (HR 0.50, CI 0.39–0.65). PARPi monotherapy also improved PFS compared to chemotherapy in BRCA-mutated patients (HR 0.62, CI 0.51–0.76). - **OS:** PARPi maintenance therapy showed better but not statistically significant results in OS in recurrent ovarian cancer (HR 0.73, CI 0.55–0.95) and BRCA-mutated patients (HR 0.74, CI 0.54–1.0). - **AEs:** PARPi therapy increased the risk of severe adverse events (AEs) compared to placebo, particularly in hematological toxicities, but these side effects were controllable with dose modification. **Conclusions:** PARPi are effective for both newly-diagnosed and recurrent ovarian cancer, providing significant PFS benefits over placebo. Despite a minor increase in severe adverse effects, they are generally well tolerated. The study highlights the importance of BRCA and HRD status in PARPi treatment decisions and suggests that maintenance therapy is beneficial for most patients with these deficiencies. However, the lack of data on OS and the short follow-up period are limitations.This systematic review and meta-analysis evaluates the efficacy and safety of PARP inhibitors (PARPi) in treating advanced ovarian cancer. The study included all phase II and III randomized controlled trials (RCTs) assessing PARPi from inception to April 13, 2022. The main outcomes were progression-free survival (PFS), overall survival (OS), and adverse events (AEs). **Results:** - **PFS:** In recurrent ovarian cancer, PARPi maintenance therapy significantly improved PFS over placebo in the total population (HR 0.34, CI 0.29–0.40), BRCA mutant (HR 0.24, CI 0.18–0.31), germline BRCA mutant (HR 0.23, CI 0.18–0.30), and BRCA wild-type cases (HR 0.50, CI 0.39–0.65). PARPi monotherapy also improved PFS compared to chemotherapy in BRCA-mutated patients (HR 0.62, CI 0.51–0.76). - **OS:** PARPi maintenance therapy showed better but not statistically significant results in OS in recurrent ovarian cancer (HR 0.73, CI 0.55–0.95) and BRCA-mutated patients (HR 0.74, CI 0.54–1.0). - **AEs:** PARPi therapy increased the risk of severe adverse events (AEs) compared to placebo, particularly in hematological toxicities, but these side effects were controllable with dose modification. **Conclusions:** PARPi are effective for both newly-diagnosed and recurrent ovarian cancer, providing significant PFS benefits over placebo. Despite a minor increase in severe adverse effects, they are generally well tolerated. The study highlights the importance of BRCA and HRD status in PARPi treatment decisions and suggests that maintenance therapy is beneficial for most patients with these deficiencies. However, the lack of data on OS and the short follow-up period are limitations.