The incidence of endometrial cancer (EC), a widely prevalent gynecological malignancy, is witnessing a global surge. Although early-stage cancer demonstrates promising outcomes, advanced cancer is associated with an unfavorable prognosis. Nevertheless, for specific pathological types or molecular subtypes of advanced EC, an accurate treatment algorithm can lead to a favorable prognosis. Here, we report a case of stage IVB EC characterized by mucinous differentiation with mismatch repair deficiencies (MMRd) who was successfully treated with combination of oxaliplatin and programmed cell death protein 1 (PD-1) inhibitor. Our findings emphasize the importance of conducting pathological and molecular typing assessments in individuals with advanced stage or recurrent EC. Additionally, combining oxaliplatin and PD-1 inhibitors may be a viable treatment option for EC with mucinous differentiation and MMRd. More representative and standardized studies are needed to consolidate this conclusion.