To elucidate surgical outcomes in pediatric/adolescent patients with chronic lateral ankle instability and os subfibulare. A retrospective chart review was conducted of pediatric/adolescent patients with chronic lateral ankle instability and os subfibulare following simultaneous ossicle resection and lateral ligament repair using suture anchors with subsequent immediate full weightbearing and active range of motion exercises for the ankle in our department between 2013 and 2017. Clinical outcomes were evaluated by comparing preoperative and final follow-up American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale (AOFAS) and Karlsson-Peterson ankle function scores. Intervals between surgery and return to physical education in school were determined. 31 feet of 15 male and 16 female patients were examined. Mean postoperative follow-up duration was 40.7 ± 12.7 (range 24-66) months. Mean AOFAS score increased significantly from 66.3 ± 2.5 (range 62-77) preoperatively to 96.5 ± 4.9 (range 87-100) at final follow-up (p < 0.001). Mean Karlsson-Peterson score increased significantly from 51.7 ± 4.0 (range 47-70) preoperatively to 95.3 ± 6.7 (range 80-100) at final follow-up (p < 0.001). Mean interval between surgery and return to physical education in school was 11.4 ± 1.6 (range 10-18) weeks. Simultaneous ossicle resection and lateral ligament repair using suture anchors with subsequent immediate full weightbearing and active ankle range of motion exercises may give excellent clinical outcomes with early return to physical activity for chronic lateral ankle instability with os subfibulare in pediatric/adolescent patients desiring an early return to physical activity. Level of evidence III.