Immigrants have lower and disproportionate use of preventive care. We use longitudinal panel data to examine how the 2014 full implementation of the ACA mandates affected change in preventive services (PS) use among immigrants that gained insurance. We used data on Foreign-Born (FB) and US-Born (USB) adults, ages 26–64 years, from the 2013/16 Medical Expenditures Panel Survey longitudinal files to examine within-person change in yearly utilization of age/sex specific United States Preventive Services Task Force (USPSTF) recommended services. We included five primary care (e.g., influenza immunization), three behavioral (e.g., diet), and seven cancer screening (e.g., mammography) measures. We used generalized estimating equations and difference-in-differences tests to assess the effects of insurance gain on: (1) change in PS utilization, and (2) reduction in utilization disparities between USB and FB adults, adjusting for predisposing, health enabling, and health needs factors. Our results showed that newly-insured FB adults substantially increased their use of all primary care checks, and exercise and diet advice. We also found improvements in use of endoscopies, two modalities of colon cancer screening, and prostate cancer screening, but not in receipt of mammography and clinical breast exams. Newly-insured FB PS use remained lower than use among continuously-insured USB adults, but some of the differences were explained by adjustment to enabling and health needs factors. Briefly, health insurance gains among immigrants translated into substantial improvements in use of recommended PS. Still, notable disparities persist among the newly-insured FB, and more so among the 1 in 5 that remain continuously uninsured.