ObjectiveTo assess the prognostic performance of the 2023 FIGO endometrial cancer staging schema. MethodsThis retrospective cohort study queried the National Cancer Database. Study population was 129,146 patients with stage I-IV endometrial cancer per the 2009 FIGO staging schema. Stage-shifting and overall survival (OS) were assessed according to the 2023 FIGO staging schema. ResultsUpstage (IA → II, 21.4%; IB → II, 53.0%) and downstage (IIIA→IA3, 22.2%) occurred in both early and advanced diseases. Inter-stage prognostic performance improved in the 2023 schema with widened 5-year OS rate difference between the earliest and highest stages (68.2% to 76.9%). Stage IA1-IIB and IIC had distinct 5-year OS rate differences (85.8–96.1% vs 75.4%). The 5-year OS rate of the 2009 stage IIIA disease was 63.9%; this was greater segregated in the 2023 schema: 88.0%, 62.4%, and 55.7% for IIIA→IA3, IIIA1, and IIIA2, respectively (inter-substage rate-difference, 32.3%). This 5-year OS rate of stage IA3 disease was comparable to the 2023 stage IB-IIB diseases (88.0% vs 85.8–89.5%). In the 2023 stage IIIC schema (micrometastasis rates: 29.6% in IIIC1 and 15.6% in IIIC2), micrometastasis and macrometastasis had the distinct 3-year OS rates in both pelvic (IIIC1-i vs IIIC1-ii, 84.9% vs 71.1%; rate-difference 13.8%) and para-aortic (IIIC2-i vs IIIC2-ii, 82.9% vs 65.2%; rate-difference 17.7%) nodal metastasis cases. The 5-year OS rate of the 2009 stage IVB disease was 23.4%; this was segregated to 25.4% for stage IVB and 19.2% for stage IVC in the 2023 staging schema (rate-difference, 6.2%). ConclusionThe 2023 FIGO endometrial cancer staging schema is a major revision from the 2009 FIGO schema. Almost doubled enriched sub-stages based on detailed anatomical metastatic site and incorporation of histological information enable more robust prognostication.