BACKGROUND: Frailty is a significant predictor of prognosis in older patients with community-acquired pneumonia (CAP). No effective therapy has been reported in frail patients with CAP, with frailty determined using the Hospital Frailty Risk Score (HFRS). AIMS: To investigate whether early physical rehabilitation intervention would effectively minimize adverse outcomes in frail older patients (determined using the HFRS) hospitalized for CAP. METHODS: This retrospective cohort analysis involved patients with CAP aged ≥ 65 years enrolled in the Japanese Diagnostic Procedure Combination Database between 2014 and 2020 and assessed as being frail. We compared 30-day mortality and readmission rates for patients who did and who did not receive physical rehabilitation within three days of admission and evaluated the association between outcomes and receiving early physical rehabilitation using Cox regression models and inverse probability weighting (IPW) for sensitivity analysis. RESULTS: The analysis involved 31,133 frail older patients hospitalized for CAP (mean age 84.3 ± 6.3 years; females, 49.1%), including 11,515 (37.0%) who received early physical rehabilitation. Cox regression analysis showed that early physical rehabilitation intervention was inversely associated with 30-day mortality and readmission rates. The IPW model also showed similar results. DISCUSSION: Early physical rehabilitation was associated with reduced risks of 30-day mortality, overall in-hospital mortality, and 30-day readmission rates in frail older patients with CAP. CONCLUSIONS: Early physical rehabilitation in frail older patients hospitalized for CAP may improve outcomes. This finding highlights the importance of simultaneously introducing the HFRS and early physical rehabilitation intervention into clinical practice for frail older patients with CAP.