Background: chemotherapy response score (CRS) is widely used to assess the response of ovarian high-grade serous carcinoma (HGSC) to chemotherapy and is based on pathological examination of omental specimens. We aimed to assess the prognostic value of CRS assessed on the uterine adnexa. Methods: a systematic review and meta-analysis were performed by searching three electronic databases from 2015 inception to September 2021. We included all studies reporting either hazard ratio (HR) with 95% confidence interval (CI) for progression-free survival (PFS) or primary PFS data, for both adnexal and omental CRS in HGSC. HRs with 95% CI were extracted and pooled by using a significant p-value < 0.05. Statistical heterogeneity was assessed by using Higgins’ I2. Results: six studies with 691 HGSC patients were included. Adnexal CRS3 vs. CRS1-2 significantly stratified PFS, with a HR of 0.572 (0.447–0.733; p < 0.001). Omental CRS3 vs. CRS1-2 significantly stratified PFS with a similar HR (HR = 0.542; 95% CI 0.444–0.662; p < 0.001). Statistical heterogeneity was 0% in both analyses. Conclusions: adnexal CRS significantly stratifies PFS in HGSC and might be used when omental CRS is not assessable.