Importance: Patients with unmet health-related social needs are at high risk for preventable health care utilization. Prior interventions to identify health-related social needs and provide navigation services with community resources have not taken place in pharmacy settings. Objective: To evaluate an enhancement of pharmacy care to reduce hospital admissions and emergency department (ED) visits among primary care patients in a Medicaid accountable care organization (ACO). Design, Setting, and Participants: This nonrandomized controlled trial was conducted from May 1, 2019, through March 4, 2021, with 1 year of follow-up. Study allocation was determined by odd or even medical record number. The study was performed at a general internal medicine practice at a large safety-net hospital in Boston, Massachusetts. Patients who qualified for the hospital's pharmacy care program (aged 18-64 years and within the third to tenth percentile for health care utilization and cost among Medicaid ACO membership) who attended a visit with a primary care clinician were eligible. Of 770 eligible patients, 577 were approached, 127 declined, and 86 could not be contacted. Interventions: Patients in the control group received usual pharmacy care focused on medication adherence. Patients in the intervention group received enhanced pharmacy care with an additional focus on identification of and intervention for health-related social needs. The intervention took place for 1 year. Main Outcomes and Measures: The primary outcome was inpatient hospital admissions and ED visits (composite outcome) in the 12 months after enrollment during the intervention period. Results: Among 364 allocated patients (mean [SD] age, 50.1 [10.1] years; 216 women [59.3%]), 35 were Hispanic of any race (9.6%) and 214 were non-Hispanic Black (58.8%). All participants were included in the intention-to-treat analysis. In analyses controlling for baseline hospital admissions and ED visits the year prior to enrollment, the enhanced pharmacy care group was not associated with the odds of having any hospital admission or ED visit (adjusted odds ratio, 0.62 [95% CI, 0.23-1.62]; P = .32) among all patients and was not associated with the visit rates among those with any visit (adjusted rate ratio, 0.93 [95% CI, 0.71-1.22]; P = .62) relative to the usual pharmacy care group in the year following enrollment. Conclusions and Relevance: The findings of this nonrandomized controlled trial suggest that inpatient and ED utilization among Medicaid ACO members at a safety-net hospital was not significantly different between groups at 1-year follow-up. Trial Registration: ClinicalTrials.gov Identifier: NCT03919084.