Introduction: Femoral shaft fractures are among the most common long-bone fractures in children and can result from both high-energy trauma, such as motor vehicle accidents, and low-energy impacts, often related to falls or sports activities. Objectives: The main objective of the study is to find the comparison of frequency of complications of paediatric femoral shaft fractures treated with hip spicca versus flexible nails. Methodology: This retrospective study was done and the data were collected from 85 patients with femoral shaft fractures were included in the study. Children aged 3 to 12 years with isolated femoral shaft fractures without additional injuries that might interfere with recovery were included in the study. Patients with associated comorbidities, prior fractures, or multiple traumas were excluded from the study. These patients were divided into two groups based on the treatment method received: hip spica casting or flexible intramedullary nailing. Results: Data were collected from 85 patients with the hip spica group averaging 5.01 years and 18 kg, while the FIN group averages 7.81 years and 25 kg, reflecting a slightly older and heavier patient profile for those treated with flexible intramedullary nailing. The hip spica group had a slightly higher incidence of open fractures (11.1%) compared to the FIN group (5%), and the average time to treatment was slightly longer for the hip spica group at 2 days versus 1 day for FIN. The analysis of complication rates indicates that hip spica casting had a higher rate of complications (40%) compared to flexible intramedullary nailing (25%). Out of the 45 patients treated with hip spica casting, 18 experienced complications, whereas only 10 out of 40 patients in the FIN group reported complications. Conclusion: It is concluded that flexible intramedullary nailing (FIN) offers a safer and more effective treatment option for pediatric femoral shaft fractures in older children, reducing complication rates and allowing faster functional recovery compared to hip spica casting.