We developed and validated a childhood eating disorder outcome scale based on outcomes associated with body mass index standard deviation score (BMI-SDS). This prospective observational study included 131 children with eating disorders (aged 5-15 years). Participants' outcomes scales were completed at the first visit and at 1, 3, 6, and 12 months. The scale evaluated 12 outcomes: body weight change (BW), eating attitude (EA), fear of being fat (FF), body image distortion (BD), menstruation (ME), perceived physical condition (PC), attending school (AS), disease recognition by school (RS), family function (FA), disease recognition by parent (RP), social adaptation (SA), and relationships with friends (RF). Responses to all items were on a four-point Likert scale. Exploratory factor analysis was used to determine the number of factors based on the 12 outcomes. The relation between outcome scale scores and BMI-SDS over the 12-month follow-up period was analyzed. Two types of factors were extracted: disease-specific factors (EA, FF, BD) and biopsychosocial factors (BW, PC, AS, FA, SA, RF). Three items (ME, RS, RP) were excluded because they showed no significant loading effect. There was a significant negative correlation between the outcome scale and BMI-SDS, and changes in outcome scale scores from baseline to 12 months were significantly associated with improvement in BMI-SDS. We developed a childhood eating disorder outcome scale characterized by disease-specific and biopsychosocial factors. Biopsychosocial management combined with a therapeutic approach for disease-specific symptoms may support body weight recovery for children with eating disorders.