ObjectivesThe integrated practice unit (IPU) aims to improve care for patients with complex medical and social needs through care coordination, medication reconciliation, and connection to community resources. This study examined the effects of IPU enrollment on emergency department (ED) utilization and health care costs among frequent ED utilizers with complex needs.MethodsWe extracted electronic health records (EHR) data from patients in a large health care system who had at least four distinct ED visits within any 6‐month period between March 1, 2018, and May 30, 2021. Interrupted time series (ITS) analyses were performed to evaluate the impact of IPU enrollment on monthly ED visits and health care costs. A control group was matched to IPU patients using a propensity score at a 3:1 ratio.ResultsWe analyzed EHRs of 775 IPU patients with a control group of 2325 patients (mean [±SD] age 43.6 [±17]; 45.8% female; 50.9% White, 42.3% Black). In the single ITS analysis, IPU enrollment was associated with a decrease of 0.24 ED visits (p < 0.001) and a cost reduction of $466.37 (p = 0.040) in the first month, followed by decreases of 0.11 ED visits (p < 0.001) and $417.61 in costs (p < 0.001) each month over the subsequent year. Our main results showed that, compared to the matched control group, IPU patients experienced 0.20 more ED visits (p < 0.001) after their fourth ED visit within 6 months, offset by a reduction of 0.02 visits (p < 0.001) each month over the next year. No significant immediate or sustained increase in costs was observed for IPU‐enrolled patients compared to the control group.ConclusionsThis quasi‐experimental study of frequent ED utilizers demonstrated an initial increase in ED visits following IPU enrollment, followed by a reduction in ED utilization over subsequent 12 months without increasing costs, supporting IPU's effectiveness in managing patients with complex needs and limited access to care.