Introduction: Physiotherapy intervention is beneficial in terms of prevention of postoperative complications, improves functional capacity, psychological aspect and enhance a better prognosis. Exercise programmes protocol of early mobility with resistance training which help patients to regain functional capacity, self-efficacy and general well-being as soon as possible are therefore a vital component of recovery after cardiac surgery. However, there was limited evidences on optimal exercise prescription for adolescent with CHD post cardiac surgery patients. The objective of this present study was to assess the efficacy of early mobilization supervised resistance training in aerobic functional capacity (VO2 max) among adolescents with congenital heart disease following cardiac surgery. Methods: This was a pre and post experimental study which also known as quasi experimental study. Prior to the surgery, 54 patients were provided with standard care, closely following the existing protocol, involving early mobilization and supervised resistance exercises for the upper and lower limbs, commencing on the first day after the surgery. 6MWT were assessed according to 3 timeframes which is pre-test during pre-operative that is baseline, mid test and post-test which during post operative and prior to discharge sessions. Results: 54 patients, 27 (50%) males and 27 (50%) were included, with a mean age of 14.6 ±2.4 years. For the within-group differences, the VO2 max value shows a better value during post test when compared to pre-test within the group. For the between-group differences, VO2 max [pre-mid 33.00 (7.07, 3.30), p= <0.038, pre-post 38.82 (7.27, 3.23), p= <0.003 and mid-post 47.04 (7.98, 3.92), p= <0.092]. Conclusion: Early mobilization supervised resistance training in physiotherapy intervention showed high significant difference on functional aerobic capacity between pre and post value among adolescent with CHD post cardiac surgery patients.