Background: For advanced or recurrent endometrial cancer (EC), therapeutic options remain scarce. Immune or antiangiogenic monotherapy has shown moderate efficacy in EC. Preclinical and clinical data showed that camrelizumab (an anti-PD-1 antibody) plus apatinib (a selective VEGFR2 inhibitor) markedly enhanced anti-tumor efficacy in multiple solid tumors. This study was designed to assess the efficacy and safety of the combination of camrelizumab and apatinib as second-line or above therapy for advanced or recurrent EC. Methods: This was an open-label, single-arm, phase II trial conducted in China. Patients with advanced or recurrent EC who progressed after at least first-line therapy received camrelizumab (200 mg, intravenously, q2w) plus apatinib (250 mg, orally, qd). Using a minimax Simon two-stage design, 21 patients were enrolled at stage I and if a complete or partial response was observed in at least four patients, the enrollment would be continued to 40 patients. The primary endpoint was the objective response rate (ORR) per RECIST version 1.1. Secondary endpoints included time to objective response (TTR), disease control rate (DCR), duration of Response (DoR), progression-free survival (PFS), overall survival (OS), time to treatment failure (TTF) and safety. Here, the results of stage I are reported. Results: Between January 20, 2020 and July 8, 2021, 21 patients were enrolled. The median age was 57 years (range 29–72). Thirteen patients (61.9%) had ECOG PS of 0, and eight patients (38.1%) received at least two prior therapies. As of November 9, 2021, the median follow-up time was 13.5 months (IQR 11.3-16.3). Among 21 evaluable patients, the confirmed ORR was 47.6% (95% CI 25.7%-70.2%) with complete response in one patient (4.8%) and partial response in nine patients (42.9%); eight patients had stable disease for a DCR of 85.7% (95% CI 63.7%-97.0%). The median PFS was 11.8 months (95% CI 5.2-14.4). Treatment-related adverse events (TRAEs) of any grade and of grade ≥ 3 were reported in 21 (100%) patients and 10 (47.6%) patients, respectively. The most common grade ≥ 3 TRAEs included gamma-glutamyltransferase increased (six [28.6%]), direct bilirubin increased (four [19.0%]), alanine aminotransferase increased (three [14.3%]), aspartate aminotransferase increased (three [14.3%]) and hyperglycaemia (three [14.3%]). Four patients (19.0%) experienced reactive cutaneous capillary endothelial proliferation, all of which were grade 1-2. No treatment-related deaths were reported. Conclusions: Camrelizumab plus apatinib demonstrated promising antitumor activity and a manageable safety profile in patients with advanced or recurrent EC after failure of at least first-line therapy. Clinical trial information: ChiCTR2000031932.