The biological age of organs may better quantify risk for health deterioration compared with chronological age. We investigated organ-specific aging patterns in a community-based cohort and assessed the associations with adverse health outcomes. Biological ages of 11 organs were estimated for 11,757 participants of the Atherosclerosis Risk in Communities (ARIC) study (55.6% women, mean age, 57.1 years) using a circulating protein-based model. Older organ ages were significantly associated with related adverse outcomes, even after accounting for chronological age; for example, older arteries and hearts were associated with an increased risk for coronary heart disease (CHD; hazard ratio [HR] per 5-year-higher age gap, 1.22; 95% CI [1.13-1.31] and 1.16 [1.07-1.26], respectively, and older lungs with lung cancer (HR 1.12 [1.09-1.16]). Hierarchical agglomerative clustering based on organ ages revealed 3 patient phenotypes: those with older organs, normal/slightly older organs, and younger organs. The patients with older organs were at higher risk for cancer (HR 1.19; 95% CI [1.08-1.31]), death (HR 1.75 [1.64-1.86]), end-stage kidney disease (HR 6.12 [4.65-8.06]), CHD (HR 1.21 [1.06-1.38]), heart failure (HR 1.92 [1.73-2.13]), infection (HR 1.56 [1.44-1.68]), and stroke (HR 1.36 [1.16-1.61]). Proteomic organ aging signatures demonstrated significant associations with multiple adverse health outcomes and may be useful for health risk identification.