Purpose: Surgical volume in ovarian cancer treatment has been discussed to influence survival. Completeness of staging in early and macroscopic complete resection in advanced ovarian cancer are indicators of treatment quality and surrogate parameters for outcome. This study examines their association with case volume in certified gynecological cancer centers. Methods: Certification audit data from ovarian cancer cases treated in 193 gynecological cancer centers certified by the German Cancer Society between 2020 and 2022 were analyzed. In our study 3,881 patients with FIGO stage I-IIIA and 7,219 patients with FIGO stage IIB-IV ovarian cancer were included. Case volume thresholds of 10, 15, 20 and 25 annual cases per hospital were explored for both quality indicators. Results: Higher-volume centers consistently performed complete surgical staging in FIGO stage I-IIIA ovarian cancer patients more frequently. For example, centers treating < 15 cases annually had a lower likelihood of complete staging (OR 0.82; 95% CI 0.69–0.98; p = 0.031). Macroscopic complete resection was achieved in 72.32–75.64% of FIGO stage IIB-IV ovarian cancer cases across all four thresholds. High-volume centers performed macroscopic complete resection about 2 percentage points more often. Conclusion: These data indicate that case volume of cancer centers is not necessarily an indicator for quality of treatment. Since certification audit data does not account for primary surgery or neoadjuvant chemotherapy, the inherent bias caused by differences in resection rates between these two treatment strategies must be acknowledged.