This research was conducted to determine whether early participation in cardiac rehabilitation (CR) reduces readmissions following heart failure (HF) hospitalization. Methods: A retrospective quasiexperimental comparison group design was used. Electronic medical records were abstracted for HF patients discharged between March 2013 and December 2017. The treatment group was defined as patients with HF who attended ≥1 CR session within 6 wk following discharge. The comparison group was defined as patients with HF without additional HF hospitalizations during the previous year, discharged to home/self-care, and did not attend CR within 6 wk. Readmission rates at 30 d and 6 wk were compared between groups using χ 2 analysis and logistic regression. Results: Out of 8613 patients with HF, 205 (2.4%) attended ≥1 CR within 6 wk post-discharge. The treatment group had lower, but not statistically significant, readmission rates than the comparison group for 30-d readmissions for HF (P = .13), and 6-wk readmission rates for HF (P = .05). The treatment group had lower all-cause readmissions at 30 d (P < .01) and 6 wk (P < .01) than the comparison group. Multivariable logistic regression revealed that early CR attendance was associated with reduced 30-d all-cause readmissions (adjusted OR = 0.4: 95% CI, 0.2-0.7) and 6-wk all-cause readmissions (adjusted OR = 0.5: 95% CI, 0.3-0.8). Conclusions: This study contributes to the existing evidence for allowing early unrestricted CR participation with the aim of improving the health of patients with HF and reducing rehospitalization rates.