Purpose: Enhanced recovery after surgery [ERAS] is an approach for standardization of perioperative care aimed at improving patient outcomes. The primary aim of this study was to determine if length of stay (LOS) differed by protocol type (ERAS vs. non-ERAS [N-ERAS]) in patients undergoing surgery for adolescent idiopathic scoliosis (AIS). Methods: A retrospective cohort study was conducted. Patient characteristics were collected and compared between groups. Differences in LOS were assessed using regression adjusting for age, sex, BMI, pre-surgical Cobb angle, levels fused and year of surgery. Results: Fifty nine ERAS patients were compared to 81 N-ERAS patients. Patients were comparable in their baseline characteristics. Median LOS was 3 days (IQR = 3–4) for the ERAS group, compared to 5 days (IQR = 4–5) for the N-ERAS group (p < 0.001). The ERAS group had a significantly lower adjusted rate of stay (RR = 0.75; 95% CI = 0.62–0.92). The ERAS group had significantly lower average pain on post-operative days 0 (least-squares-mean [LSM] 2.66 vs. 4.41, p < 0.001), POD1 (LSM 3.12 vs. 4.48, p < 0.001) and POD5 (LSM 2.84 vs. 4.42, p = 0.035). The ERAS group had lower opioid consumption (p < 0.001). LOS was predicted by the number of protocol elements received; those receiving two (RR = 1.54 95% CI = 1.05–2.24), one (RR = 1.49; 95% CI = 1.09–2.03) or none (RR = 1.60, 95% CI = 1.21–2.13) had significantly longer rates of stay than those receiving all four. Conclusion: Adoption of modified ERAS-based protocol for patients undergoing PSF for AIS led to significant reduction in LOS, average pain scores, and opioid consumption.