Objectives This study evaluates the impact of frailty, which is a state of increased vulnerability to stressors, on 30-day and 1-year mortality among elderly patients with community-acquired pneumonia (CAP). The main hypothesis is that frailty is an independent predictor of prognosis in elderly CAP patients. Design Prospective, observational, follow-up cohort study. Setting A 2000-bed tertiary care hospital in Beijing, China. Participants Consecutive CAP patients aged >= 65 years admitted to the geriatric department of our hospital between September 2017 and February 2019. Main outcome measures The primary outcomes were all-cause mortality at 30 days and 1 year after hospital admission. The impact of frailty (defined by frailty phenotype) on 30-day and 1-year mortality of elderly patients with CAP was assessed by Cox regression analysis. Results The cohort included 256 patients. The median (IQR) age was 86 (81-90) years, and 180 (70.3%) participants were men. A total of 171/256 (66.8%) patients were frail. The prevalence of frailty was significantly associated with older age, female gender, lower body mass index, comorbidities, limitations in activities of daily living (ADLs) and poor nutritional status. Frail participants were significantly more likely to have severe CAP (SCAP) than non-frail counterparts (28.65% vs 9.41%, p<0.001). The 1-year mortality risk was approximately threefold higher in frail patients (adjusted HR, 2.70; 95% CI, 1.69 to 4.39) than non-frail patients. Subgroup analysis of patients with SCAP showed that the 1-year mortality risk was approximately threefold higher in the frail group (adjusted HR, 2.87; 95% CI, 1.58 to 4.96) than in the non-frail group. The association between frailty and 30-day mortality was not significant. Conclusions These findings suggest that frailty is strongly associated with SCAP and higher 1-year mortality in elderly patients with CAP, and frailty should be detected early to improve the management of these patients.