Background: Class 3 obesity is composed of morbid (BMI 40–49 kg/m2) and extreme (BMI ≥ 50 kg/m2) subgroups. Adverse perinatal outcomes have been associated with obesity; however, data on breastfeeding (BF) initiation for women in either group remains limited. Objective: To compare BF initiation rates (exclusive or partial BF) and related comorbidities of 890 women with morbid and 890 with extreme obesity matched by race, parity, and year of delivery. Methods: Retrospective cohort study of women who delivered singletons at ≥ 34 weeks gestation (2013–2021). Those who had bariatric surgery or infants with major malformations were excluded. Results: Both groups were similar in: primiparity (38%), age (29y), white race (58%), African American (36%), current (10 vs 12%) and former (25 vs 27%) smokers, gestational hypertension (15 vs 16%), polycystic ovary syndrome (5 vs 7%), gastroesophageal reflux disease (10 vs 10%), and anemia (17 vs 17%). Women in the extreme group had a higher prevalence of gestational (17 vs 12%) and pregestational diabetes (12 vs 6%), chronic hypertension (41 vs 17%), severe preeclampsia (18 vs 12%), obstructive sleep apnea (12 vs 3%), asthma (22 vs 16%), and cesarean deliveries (62 vs 44%). Intention to BF (64 vs 71%), exclusive BF (23 vs 34%), and BF initiation (57 vs 64%) rates were lower in the extreme obesity group at discharge. Conclusion: Higher frequency of comorbidities in the extreme obesity group highlights the need for antenatal, intrapartum, and postpartum targeted interventions if the benefits of BF to mothers and infants are to be realized.