Importance: Medicare Advantage (MA), a private insurance plan option, now covers one-third of all Medicare beneficiaries. Although patients with cardiovascular disease enrolled in MA have been reported to receive higher quality of care in the ambulatory setting than patients enrolled in fee-for-service (FFS) Medicare, it is unclear whether MA is associated with higher quality in patients hospitalized with heart failure, or alternatively, if incentives to reduce utilization under MA plans may be associated with worse care. Objective: To determine whether there are differences in quality of care received and in-hospital outcomes among patients enrolled in MA vs FFS Medicare. Design, Setting, and Participants: Observational, retrospective cohort study of patients hospitalized with heart failure in hospitals participating in the Get With the Guidelines-Heart Failure registry. Exposures: Medicare Advantage enrollment. Main Outcomes and Measures: In-hospital mortality, discharge disposition, length of stay, and 4 heart failure achievement measures. Results: Of 262626 patients hospitalized with heart failure, 93549 (35.6%) were enrolled in MA and 169077 (64.4%) in FFS Medicare. The median (interquartile range) age was 78 (70-85) years for patients enrolled in MA and 78 (69-86) years for patients enrolled in FFS Medicare. Standard mean differences in age, sex, prevalence of comorbidities, or objective measures on admission, including vital signs and laboratory values, were less than 10%. After adjustment, there were no statistically significant differences in receipt of evidence-based β-blockers when indicated; angiotensin-converting enzyme inhibitor, angiotensin II receptor blockers, or angiotensin receptor-neprilysin inhibitors at discharge; measurement of left ventricular function; and postdischarge appointments by Medicare insurance type. Patients enrolled in MA, however, had higher odds of being discharged directly home (adjusted odds ratio [AOR], 1.16; 95% CI, 1.13-1.19; P <.001) relative to patients enrolled in FFS Medicare and lower odds of being discharged within 4 days (AOR, 0.97; 95% CI, 0.93-1.00; P =.04). There was no significant difference in in-hospital mortality between patients with MA and patients with FFS Medicare (AOR, 0.98; 95% CI, 0.92-1.03; P =.42). Conclusions and Relevance: Among patients hospitalized with heart failure, no observable benefit was noted in quality of care or in-hospital mortality between those enrolled in MA vs FFS Medicare, except lower use of post-acute care facilities. As MA continues to grow, it will be important to ensure that participating private plans provide an added value to the patients they cover to justify the higher administrative costs compared with traditional FFS Medicare.