Reports on different types of surgical procedures show that night-time surgeries are often associated with a high number of complications than daytime surgeries. However, there are no data, and hence evidence that relate the outcome of supracondylar humeral fractures in children to the time of the day when the respective surgical procedure is implemented. In this study, we analyze the clinical and radiological outcomes of pediatric supracondylar humeral fractures surgically treated during daytime and night-time hours. In total, 91 patients with Gartland type-3 fractures were included; 47 patients treated between 0800 and 1700 h were defined as the daytime group and 44 patients treated between 1701 and 0759 h were defined as the after-hours group. Age, sex, affected side, fracture type, and day and time of operation were recorded. Any preoperative neurovascular injuries, open fractures, or ipsilateral fractures were noted. The surgical method, use of a medial pin or pins, operation time, any postoperative neurovascular complications, extent of successful reduction, fixation rate, any resultant deformity, and functional loss rate were evaluated. The two groups did not differ significantly in terms of operation time, open reduction rate, rate of poor reduction, extent of poor functional outcomes, or induction of deformity (P>0.05). The poor fixation rate was significantly greater in the after-hours group than in the daytime group (P<0.05). No significant between-group differences were evident in age, sex, affected side, or length of postoperative follow-up (all P-values>0.05). After-hours treatment of displaced supracondylar humeral fractures in children is associated with a higher poor fixation rate compared with daytime procedures. Level of evidence: therapeutic study (retrospective comparative study), Level III.