The geriatric nutritional risk index (GNRI) is associated with the prognosis of many diseases. However, the association between the GNRI and the prognosis of patients aged ≥65 years with severe community-acquired pneumonia (SCAP) has not been studied. We aimed to evaluate the prognostic value of GNRI in elderly SCAP patients.This study retrospectively analyzed the clinical data of 346 patients aged ≥65 years with SCAP from December 2013 to September 2019. Patients were divided into 4 groups by the GNRI. The chi-square test or student's t test was used to compare the differences between the groups. Logistic regression analysis was used to evaluate the factors that affect prognosis. The receiver operating characteristic curve was used to compare the prognostic performance of the GNRI with other indicators. A GNRI-based nomogram was established based on the result of the multivariate analysis.Two hundred nine (60.4%) patients had a poor prognosis. GNRI scores were significantly lower in the poor prognosis group than in the group with a good prognosis. In the multivariate analysis, gender, mean arterial pressure, neutrophil counts, and the GNRI were independently correlated with the prognosis of elderly patients. The GNRI was a significantly better predictor for poor prognosis than other indicators. The GNRI-based nomogram had excellent prediction capabilities.GNRI is a simple and effective prognostic indicator for elderly patients with SCAP, and a GNRI-based nomogram can aid in developing individualized treatment plans for elderly patients with SCAP.