Five decades into the era of mass incarceration, a growing number of older adults have experienced criminal legal involvement (CLI) in their lifetime. Studies have shown that prior incarceration is associated with substantial disease burden, but little is known about the distinct needs and utilization patterns of middle-aged and older adults with lifetime CLI compared to those without. Using a nationally representative data set, we tested the association between lifetime CLI exposure and use of acute care services among middle-aged and older adults. Our sample included 44,007 US adults (25,074 middle-aged-50-64 years; 18,709 older- ≥65 years) who participated in the National Survey of Drug Use and Health (2015-2019). The data is publicly available. Our independent variable was lifetime CLI. Using separate negative binomial regression models for middle-aged and older adults, we tested the association between lifetime CLI and acute healthcare utilization (ED visits and nights spent inpatient) controlling for relevant sociodemographic covariates. For middle-aged respondents, 19.1% reported lifetime CLI; for older adults, the rate of exposure was 9.6%. In multivariate models, CLI was associated with increased ED visits in middle-aged adults (IRR 1.18, 95% CI 1.06-1.31) but not older adults (IRR 0.99, 95% CI 0.85-1.16). CLI was associated with increased nights hospitalized in both groups (middle-aged: IRR 1.33, 95% CI 1.08-1.62; older adults: IRR 1.26, 95% CI 1.01, 1.57). Middle-aged and older adults with lifetime CLI experience higher rates of acute care utilization than their peers with no lifetime CLI, even after adjustment for confounders. As the cohort of adults from the era of mass incarceration ages, understanding the mechanisms by which lifetime CLI impacts health outcomes is crucial in designing interventions to improve outcomes and reduce unnecessary acute healthcare utilization.