Aims. The aim of this study was to compare outcomes of guided growth and varus osteotomy in treating Kalamchi type II avascular necrosis (AVN) after open reduction and Pemberton acetabuloplasty for developmental dysplasia of the hip (DDH). Methods. This retrospective study reviewed patients undergoing guided growth or varus osteotomy for Kalamchi type II AVN between September 2009 and January 2019. All children who had undergone open reduction and Pemberton acetabuloplasty for DDH with a minimum two-year follow-up were enrolled in the study. Demographic and radiological data, which included the head-shaft angle (HSA), neck-shaft angle (NSA), articulotrochanteric distance (ATD), Sharp angle (SA), and lateral centre-edge angle (LCEA) at baseline, two years, and at the extended follow-up, were compared. Revision rates were evaluated. Clinical outcomes using the Harris Hip Score were assessed two years postoperatively. Results. A total of 24 patients underwent guided growth and 19 underwent varus osteotomy, over a mean period of 3.3 years (95% confidence interval (CI) 2.8 to 3.8) and 5.2 years (95% CI 4.5 to 6.0), respectively. There were no differences in demographic and preoperative radiological data, except for a younger age at time of acetabuloplasty and larger ATD for the osteotomy group. The HSA did not differ at two years and the extended follow-up because of postoperative rebound in the osteotomy group. The NSA of the osteotomy group remained smaller postoperatively. There were no significant differences in the follow-up ATD, SA, and LCEA, except for a smaller two-year ATD of the osteotomy group. Seven patients (29.2%) in the guided growth group underwent revision surgery and none in the osteotomy group. The Harris Hip Score was similar between groups. Conclusion. Guided growth and varus osteotomy had comparable results in improving caput valgum deformity, given the rebound of lateral tilting of the physis after osteotomy correction. There were no differences in clinical outcomes at two years postoperatively. Cite this article: Bone Joint J 2022;104-B(7):902–908