For displaced supracondylar humeral fractures in children, in the event of closed reduction failure, anatomic reduction is achieved via open reduction techniques; however, there are no confirmative reports among the published open reduction approaches that deliver the best functional and cosmetic results. Here, we compared long-term functional and cosmetic results of different surgical approaches. Retrospective cohort study. Ankara Education and Research Hospital/Turkey. Secondary care hospital and trauma center. We evaluated 70 surgically treated Gartland type 3 supracondylar humeral fractures. Patients, with detailed history record, were divided into 5 groups with respect to surgery methods. All patients were treated surgically using closed reduction and percutaneous pinning or 4 different open reduction approaches and percutaneous pinning. Flynn cosmetic and functional score results were compared between surgical groups. Posterior open reduction and triceps transection groups showed worst results, whereas medial and lateral open reduction groups showed good to excellent results similar to closed reduction group. Medial and lateral approaches demonstrated better functional results than posterior and triceps transection approaches. Posterior approaches lead to restrictions in extension and poor functional results. In the posterior approach, transecting triceps from olecranon does not benefit from fracture reduction but results in loss of triceps strength and should be avoided. In failed closed reduction, medial and lateral open reduction approaches lead to similar cosmetic outcomes and functional results that are only slightly worse compared with those in closed reduction. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.