Background <p>The effectiveness of PD-1 inhibitors for treating endometrial cancer (EC) remains a topic of debate. Guidelines lack consistency regarding the preferred treatments for advanced cases, as well as for patients experiencing metastasis or recurrence. Thus, our goal was to assess the efficacy of Dostarlimab, a PD-1 inhibitor, in EC by incorporating data from clinical trials to create a more comprehensive database.</p> Methods <p>We conducted a thorough and systematic search of the Scopus, Medline, Embase, and Web of Science databases, identifying all eligible studies on Dostarlimab’s efficacy in endometrial cancer.</p> Results <p>Our data demonstrated that the hazard ratio of OS in the pooled proportion of participants was 43%. The hazard ratio of PFS in the pooled proportion of EC patients was 0.39 (95% CI: 0.31–0.49). The overall analysis generated a probability of remaining in response of 72.71% (95% CI: 60.94–84.49%). In addition, pooling the results from both subgroups of EC patients, including proficient mismatch repair (pMMR) and deficient mismatch repair (dMMR), yielded an ORR of 33.93% (95% CI: 21.49–46.37%) and a DCR of 51.73% (95% CI: 37.0–66.42%). Overall, the deficient mismatch repair group compared to the proficient mismatch repair group showed better outcomes. Finally, the dMMR subgroup showed a median PFS of 7.86 months (95% CI: 4.46–11.26).</p> Conclusion <p>Dostarlimab demonstrated limited efficacy in patients with pMMR EC, but it represented better outcomes in those with dMMR EC.</p>