Objective: This study compared the impact of minimally invasive surgery (MIS) and open spinal deformity corrections on the paraspinal musculature and soft tissues in adolescent idiopathic scoliosis (AIS) patients by analyzing early postoperative serum tissue injury markers and later radiographic evidence of muscle atrophy within the paraspinal musculature until 6-month and 2-year postoperative follow-ups. Methods: Prospective data were collected at a single tertiary care center from January 1, 2015 to November 30, 2020. Demographic, clinical, laboratory, and radiographic data, including postoperative magnetic resonance imaging, were collected at various intervals. Results: Forty-four patients met the inclusion criteria. The mean estimated blood loss and mean operative time differed significantly between the groups. On postoperative day 1, the Open group had significantly higher serum aldolase concentrations (18.2±7.6 mU/mL vs. 12.9±4.2 mU/mL) and creatine kinase (CK) values (3,003.1±60.1 IU/L vs. 1,649.4±40.6 IU/L) than the MIS patients. In the Open group, serum aldolase and CK levels remained higher through postoperative day 4. The normalized difference in the loss of paraspinal muscle mass was higher in the Open group than in the MIS group. Patient-reported outcomes improved in both groups, but there were no significant between-group differences. Both groups reported similar complication rates. Conclusion In patients with AIS, MIS was associated with lower tissue injury markers and muscle atrophy than open surgical correction in the early postoperative period. While this difference may be associated with decreased blood loss and shorter hospital stays seen in MIS, it did not result in a significant difference in clinical outcomes versus open surgery.