Health systems invest in coordination and collaboration between emergency departments (ED) and after-hours primary care providers (AHPCs) to alleviate pressure on the acute care chain. There are substantial gaps in the existing evidence, limited in sample size, follow-up care, and costs. We assess whether acute care collaborations (ACCs) are associated with decreased ED utilization, hospital admission rates, and lower costs per patient journey, compared with stand-alone facilities. The design is a quasi-experimental study using claims data. The study included 610 845 patients in the Netherlands (2017). Patient visits in ACCs were compared to stand-alone EDs and AHPCs. The number of comorbidities was similar in both groups. Multiple logistic and gamma regressions were used to determine whether patient visits to ACCs were negatively associated with ED utilization, hospital admission rates, and costs. Logistic regression analysis did not find an association between patients visiting ACCs and ED utilization compared to patients visiting stand-alone facilities [odds ratio (OR), 1.01; 95% confidence interval (CI), 1.00–1.03]. However, patients in ACCs were associated with an increase in hospital admissions (OR, 1.07; 95% CI, 1.04–1.09). ACCs were associated with higher total costs incurred during the patient journey (OR, 1.02; 95% CI, 1.01–1.03). Collaboration between EDs and AHPCs was not associated with ED utilization, but was associated with increased hospital admission rates, and higher costs. These collaborations do not seem to improve health systems’ financial sustainability.