Background: Supracondylar fractures are a common type of elbow fracture in children, and Gartland type III fractures are the most severe form of this injury. These fractures may be treated with either closed reduction and percutaneous pinning or open reduction and internal fixation using pins. Objective: To evaluate the outcome of pediatric stiffness in Gartland type III supracondylar fractures using the Flynn's criteria. Materials and Methods: A Multicentered based prospective study was performed in 250 Beded District Hospital, Chapainawabganj, Rajshahi, Bangladesh, from January 2021 to December 2022. A total of 80 patients with displaced type III extension supracondylar fractures were included, all of whom were treated at two separate facilities in a systematic way. Closed reduction and percutaneous cross-pinning were the major components of treatment at (n = 43). ORIF was the treatment plan (n = 37) for patients. Their stiffness was evaluated over a 6-month follow-up period. Result: A total of 80 displaced type III extension supracondylar fractures treated primarily closed reduction and percutaneous cross-pinning (n=43), while the other used primarily open reduction and internal fixation (n=37) with two lateral parallel pins (n=11), cross pins (n=11) and two lateral and one medial pin (n =15), 28 patients (75.6%) had an excellent result, six patients (18.9%) had a good result, two patients (4.6%) had a fair result, and one patient (2.7%) had a poor result in the ORIF group. In the CRPF group, 33 (76.7%) patients had an excellent result, seven (16.2%) patients had a good result, two (4.6%) patients had a fair result, and one (2.4%) patient had a poor result. The stability and configuration of the fracture open and closed reduction groups were not statistically significant according to Flynn's criteria (P>0.05). Concision: This study provides valuable information on the evaluation of pediatric stiffness in Gartland type III supracondylar fractures and highlights the need for careful follow-up to detect and manage any potential stiffness. Although closed reduction did not show any superiority over open reduction, it was suggested as the first treatment choice due to its low morbidity and short hospital stay.