Aims To examine the temporal trends and factors associated with national cardiac rehabilitation (CR) referral and compare the risk of hospital readmission and mortality in those referred for CR versus no referral. Methods and results This cohort study includes all adult patients alive 120 days from incident heart failure (HF) identified by the Danish Heart Failure Registry (n = 33 257) between 2010 and 2018. Multivariable logistic regression models were used to assess the association between CR referral and patient factors and acute all-cause hospital readmission and mortality at 1 year following HF admission. Overall, 46.7% of HF patients were referred to CR, increasing from 31.7% in 2010 to 52.2% in 2018. Several factors were associated with lower odds of CR referral: male sex [odds ratio (OR): 0.85; 95% confidence interval: 0.80-0.89], older age, unemployment, retirement, living alone, non-Danish ethnic origin, low educational level, New York Heart Association (NYHA) class IV vs. I (OR: 0.75; 0.60-0.95), left ventricular ejection fraction >40%, and comorbidity (stroke, chronic kidney disease, atrial fibrillation/flutter, and diabetes). Myocardial infarction, arthritis, coronary artery bypass grafting, percutaneous coronary intervention, valvular surgery, NYHA class II, and use of angiotensin-converting enzyme inhibitors were associated with higher odds of CR referral. CR referral was associated with lower risk of acute all-cause readmission (OR: 0.92; 0.87-0.97) and all-cause mortality (OR: 0.65; 0.58-0.72). Conclusion Although increased over time, only one in two HF patients in Denmark were referred to CR in 2018. Strategies are needed to reduce referral disparities, focusing on subgroups of patients at highest risk of non-referral.