Background Patients with obesity and advanced heart failure face unique challenges on the path to heart transplantation. There are limited data on waitlist and transplantation outcomes in this population. We aimed to evaluate the impact of obesity on heart transplantation outcomes, and to investigate the effects of the new organ procurement and transplantation network allocation system in this population. Methods and Results This cohort study of adult patients listed for heart transplant used the United Network for Organ Sharing database from January 2006 to June 2020. Patients were stratified by body mass index (BMI) (18.5–24.9, 25–29.9, 30–34.9, 35–39.9, and 40–55 kg/m ² ). Recipient characteristics and donor characteristics were analyzed. Outcomes analyzed included transplantation, waitlist death, and posttransplant death. BMI 18.5 to 24.9 kg/m ² was used as the reference compared with progressive BMI categories. There were 46 645 patients listed for transplantation. Patients in higher BMI categories were less likely to be transplanted. The lowest likelihood of transplantation was in the highest BMI category, 40 to 55 kg/m ² (hazard ratio [HR], 0.19 [0.05–0.76]; P =0.02). Patients within the 2 highest BMI categories had higher risk of posttransplantation death (HR, 1.29; P <0.001 and HR, 1.65; P <0.001, respectively). Left ventricular assist devices among patients in obese BMI categories decreased after the allocation system change ( P <0.001, all). After the change, patients with obesity were more likely to undergo transplantation (BMI 30–35 kg/m ² : HR, 1.31 [1.18–1.46], P <0.001; BMI 35–55 kg/m ² : HR, 1.29 [1.06–1.58]; P =0.01). Conclusions There was an inverse relationship between BMI and likelihood of heart transplantation. Higher BMI was associated with increased risk of posttransplant mortality. Patients with obesity were more likely to undergo transplantation under the revised allocation system.