We estimated hypertension and diabetes prevalence among US homeless adults compared with the general population, and investigated prevalence trends. We systematically searched 5 databases for published studies (1980-2014) that included hypertension or diabetes prevalence for US homeless adults, pooled disease prevalence, and explored heterogeneity sources. We used the National Health Interview Survey for comparison. We included data from 97366 homeless adults. The pooled prevalence of self-reported hypertension was 27.0% (95% confidence interval=23.8%, 29.9%; n=43 studies) and of diabetes was 8.0% (95% confidence interval=6.8%, 9.2%; n=39 studies). We found no difference in hypertension or diabetes prevalence between the homeless and general population. Additional health care and housing resources are needed to meet the significant, growing burden of chronic disease in the homeless population.