Background: In children, femoral shaft fractures are usually treated by initial performance and durability for 3 to 4 weeks, followed by an additional period of immobilization in a hip spica cast until union occurs. However, such treatment would involve prolonged hospital stays, thereby increasing the cost and occupancy of hospital beds. Early hip spica cast application of femoral shaft fractures in children is a valuable alternative to the traditional treatment method. It allows for a short hospital stay, thereby avoiding all the problems associated with prolonged hospitalization. Methods: This prospective study was conducted on 20 patients. Multicentered based non-randomized evaluations were performed in Modernized District Hospital, Joypurhat, and Rajshahi Medical College Hospital, Rajshahi, Bangladesh, from January 2020 to April 2022. With femur shaft fractures over two years. All the children of both sexes from 2 to 12 years of age with fractures shaft of the femur presented within day one of injury. Follow-up was done in OPD for up to 6 months. The functional result was assessed according to Flynn’s scoring criteria. Results: The mean age of the patient was 5.65 years, ranging from 2 to 12 years. The male-female ratio was 3:1. The mean duration of hospital stay was 4.1 days. Radiological union in all cases was achieved in a mean time of 7.65 weeks. Full weight-bearing was possible in a mean time of 10.07 weeks. The result was excellent in sixteen patients (80%), successful in two (10%), and poor in two patients (10%). Conclusions: Early spica cast is a simple, effective, and definite treatment method with minimal complications and acceptable results in the pediatric age group.