This study aimed to develop an exercise program for childhood cancer survivors and examine its feasibility and effects on improvements in physical fitness, muscle strength, and body composition. A tailored exercise program for childhood cancer survivors was developed through 8 systematic procedures, including a review of literature, physical activity survey, qualitative study, the first expert panel discussion, drafting an evidence-based exercise program, secondary expert panel discussion, revising the exercise program, and conducting feasibility and pilot study. For the feasibility and pilot study, 10 childhood cancer survivors (mean age 16.30 ± 1.77 years) participated, divided into either an exercise or a control group. Participants in the exercise group participated in the exercise program for 6 weeks. Based on preliminary studies, the exercise programs consisted of home-based and supervised exercise programs, including resistance and sports, conducted for 6 weeks. The body composition was measured, and a 6-minute walk test, grip strength, vertical jump, sit-up, push-up, chair stand test, and sit and reach test was conducted. After completing the exercise program, muscular endurance (sit-up test, p-value = 0.039) and lower body strength (chair stand test, p-value = 0.010) were significantly increased in the exercise group compared to the control group. Fat mass significantly decreased in the exercise group compared to the control group (p-value = 0.010). In conclusion, the exercise program developed in this study demonstrated feasibility and effectiveness in reducing body fat mass and improving muscular endurance and lower body strength in childhood cancer survivors.