Atrial fibrillation (AF) and heart failure (HF), common in older adults, are associated with poor outcomes. However, little is known about their impact, independent of each other. We studied 5,673 community-dwelling adults aged ≥ 65 years in the Cardiovascular Health Study. Baseline prevalent AF and HF were centrally adjudicated, and 116 patients had AF only, 219 had HF only, 39 had both, and 5,263 had neither. The Cox proportional hazards model was used to estimate age-gender-race-adjusted hazard ratio (aHR) and 95% confidence intervals (CIs) for all-cause, cardiovascular (CV), and non-CV mortalities. Participants had a mean age of 73 years (± 6 years), 58% were women, and 15% African-American. During 13 years of follow-up, all-cause mortality occurred in 43%, 66%, 74%, and 85% of those with neither, AF only, HF only, and both, respectively. Compared with neither, aHR (95% CIs) for all-cause mortality associated with AF only, HF only, and both was 1.36 (1.08 to 1.72), 2.31 (1.97 to 2.71), and 3.04 (2.15 to 4.29), respectively. Similar associations were observed with CV mortality, but HF only also had greater non-CV mortality (aHR 1.72, 95% CI 1.35 to 2.18). Compared with AF alone, aHR (95% CIs) associated with HF alone for all-cause, CV, and non-CV mortalities was 1.69 (1.29 to 2.23), 1.73 (1.20 to 2.51), and 1.64 (1.09 to 2.46), respectively. Compared with HF alone, those with both conditions had greater CV but not all-cause mortality. In conclusion, community-dwelling older adults with AF have greater mortality than those without but lesser than those with HF, and both conditions were associated with greater CV and all-cause mortalities, whereas only those with HF had greater non-CV mortality.