Emergency department (ED) use postpartum is a common and often-preventable event. Unlike traditional obstetrics models, the Ontario midwifery model offers early care postpartum. To assess whether postpartum ED use differs between women who received perinatal care in midwifery-model care vs in traditional obstetrics-model care. This retrospective population-based cohort study took place in Ontario, Canada, where public health care is universally funded. Participants included women who were low risk and primiparous and gave birth to a live baby in an Ontario hospital between 2012 and 2018. Data were collected from April 2012 to March 2018 and analyzed from June 2022 to April 2023. Perinatal care clinician, namely, a midwife or obstetrician. : Any unscheduled ED visit 42 days postpartum or less. Poisson regression models compared ED use between women with midwifery-model care vs obstetrics-model care, weighting by propensity score-based overlap weights. Among 104 995 primiparous women aged 11 to 50 years, those in midwifery-model care received a median (IQR) of 7 (6-8) postpartum visits, compared with 0 (0-1) visits among those receiving obstetrics-model care. Unscheduled ED visits 42 days or less postpartum occurred for 1549 of 23 124 women (6.7%) with midwifery-model care compared with 6902 of 81 871 women (8.4%) with traditional obstetrics-model care (adjusted relative risks [aRR], 0.78; 95% CI, 0.73-0.83). Similar aRRs were seen in women with a spontaneous vaginal birth (aRR, 0.71; 95% CI, 0.65-0.78) or assisted vaginal birth (aRR, 0.70; 95% CI, 0.59-0.82) but not those with a cesarean birth (aRR, 0.94; 95% CI, 0.86-1.03) or those with intrapartum transfer of care between a midwife and obstetrician (aRR, 0.94; 95% CI, 0.87-1.04). ED use 7 days or less postpartum was also lower among women receiving midwifery model care (aRR, 0.70; 95% CI, 0.65-0.77). In this cohort study, midwifery-model care was associated with less postpartum ED use than traditional obstetrics-model care among women who had low risk and were primiparous, which may be due to early access to postpartum care provided by Ontario midwives.