Background: Olaparib, a poly (ADP-ribose) polymerase inhibitor (PARPi), monotherapy as first-line maintenance treatment has shown to be cost-effective in ovarian cancer (OC) patients with BRCA mutations in Spain. Regardless of BRCA status, patients with homologous recombination deficiency positive (HRD+) also benefit from PARPi following first-line platinum-based therapy. PAOLA-1 trial confirmed that adding Olaparib to bevacizumab (BEV) significantly increased progression-free survival (PFS) in OC patients. The aim of this study was to assess the cost-effectiveness of Olaparib plus BEV versus BEV monotherapy for the maintenance treatment of HRD+ advanced OC patients after response to first-line platinum-based therapy plus BEV from Spanish National Health System perspective. Methods: A lifetime partitioned survival model with monthly cycles and four health states (PFS, first progression, second progression, and death) was developed. Long-term survival defined as 60 months was included in the mixed survival model as a landmark to extrapolate PFS from the PAOLA-1 trial. Weibull distribution was selected as the most accurate survival model for PFS extrapolation. Time to second progression, and overall survival (OS) were extrapolated using parametric survival models. Mortality was obtained from the OS and adjusted by Spanish mortality rates. Health state utilities and adverse event (AE) frequencies were obtained from PAOLA-1. An expert panel validated data and assumptions. Direct costs including drug acquisition and administration, follow-up, subsequent therapies, AE, and end-of-life were obtained from local sources. A 3% annual discount rate was applied to costs and outcomes. The incremental cost-effectiveness ratio (ICER) was calculated as cost per quality-adjusted life-years (QALYs) gained. One-way and probabilistic sensitivity analyses (PSA) were performed to assess the robustness of the model. Results: Base-case analysis of Olaparib plus BEV compared with BEV showed an ICER of €24,371 per QALY gained. Discount rates applied to outcomes and the cost of Olaparib generated the most significant changes in the ICER. PSA demonstrated that Olaparib plus BEV had a 49.5% and 90.3% probability of being cost-effective versus BEV at a willingness-to-pay of €25,000 and €60,000 per QALY gained, respectively. Conclusions: Olaparib plus BEV is a cost-effective maintenance therapy compared with BEV for patients with HRD+ advanced OC in Spain.