We examined the association between dietary potassium intake and all-cause and cause-specific mortality among community-dwelling older adults. Potassium intake was assessed with a food frequency questionnaire administered to 1,363 older adults (mean age 71.0 ± 10.6 years). Cox proportional hazard regressions estimated hazard ratios for sex-specific quintiles of calorie-adjusted potassium in relation to all-cause and cause-specific (cardiovascular disease, CVD, and stroke) mortality, adjusting for numerous covariates. There were 855 deaths (63% mortality) during the 20-year follow-up. Relative to the third quintile, potassium intake in the lowest quintile only was associated with increased risk of all-cause mortality (fully-adjusted hazard ratio 1.33; 95% CI 1.06, 1.67). Potassium intake was not significantly associated with CVD or stroke mortality. These results suggest that low potassium intake is associated with increased risk of mortality independent of overall health status. Ensuring adequate potassium in the diet may be an important strategy for reducing risk of earlier mortality among older adults.