Objectives. To evaluate the effectiveness of a novel health care access program (ActionHealthNYC) for uninsured immigrants. Methods. The evaluation was conducted as a randomized controlled trial in New York City from May 2016 through June 2017. Using baseline and follow-up survey data, we assessed health care access, patient experience, and health status. Results. At baseline, 25% of participants had a regular source of care; two thirds had visited a doctor in the past year and reported 2.5 visits in the past 12 months, on average. Nine to 12 months later, intervention participants were 1.2 times more likely to report having a primary care provider (58% vs 46%), were 1.2 times more likely to have seen a doctor in the past 9 months (91% vs 77%), and had 1.5 times more health care visits (4.1 vs 2.9) compared with control participants. Conclusions. ActionHealthNYC increased health care access among program participants. Public Health Implications. State and local policymakers should build on the progress that has been made over the last decade to expand and improve access to health care for uninsured immigrants.