Introduction: Early cardiac rehabilitation using non-invasive ventilation (NIV) and aerobic exercise may reduce the length of hospital stay in patients with heart failure (HF), however, there is still no evidence of this effect on patients in the intensive care unit (ICU). Objectives: to investigate the effects of aerobic exercise (AE) performed simultaneously with non-invasive ventilation (NIV) on the length of intensive care stay (LICUS) in patients diagnosed with decompensated heart failure (HF) admitted to the intensive care units (ICU). Methods: Twenty-eight patients admitted to the intensive care unit (ICU) because of decompensation of HF were randomised into two groups: the intervention group (AEþNIV), and a control group. The intervention group’s treatment strategy involved simultaneous AE with NIV daily. The control group performed non-simultaneous AE and NIV daily during their ICU stay. The primary outcome was LICUS. The secondary outcomes were the length of hospital stay, peripheral and respiratory muscle strength, functional status, functional classification, and exercise tolerance. Results: The mean LICUS was shorter in AEþNIV than in the control group (6.3±4.7days vs 8.3 ±3.6days, respectively; p¼0.015). Secondary outcomes were similar between groups, except for exercise hemodynamics, which was improved in AEþNIV, as showed by the decreased diastolic blood pressure immediately after the exercise tolerance test. Conclusion: The use of AE simultaneous with NIV reduced the LICUS of patients admitted to the ICU because of decompensated HF. This innovative approach is a promising tool for accelerating ICU discharge during the in-hospital rehabilitation of patients with HF.