Background: Juvenile idiopathic arthritis (JIA) is a common rheumatic disorder in children with a chronic relapsing-remitting course that affects physical growth and requires frequent adjustment of the treatment regimen. The study was aimed to evaluate the effect of an intervention program on maternal participation for the management and the nutritional status of children with JIA. A quasi-experimental design was conducted at the Pediatric Rheumatology and Immunology Unit at Zagazig University Hospital and Al Ahrar Hospital on a sample of 52 mothers and their children. Three tools were used as follows; a structured interview questionnaire, the maternal participation in the management of their children questionnaire, and the nutritional assessment sheet. Results: the total mean scores of maternal participation in the management of their children with JIA and the means of weight, height, and body mass index (BMI) of the studied children were significantly improved after the implementation of the intervention. (P<0.001). Conclusion: the intervention program was effective in improving maternal participation in the management of their children with JIA. The study findings also revealed a statistically significant increase in the percentage of healthy-weight children after the implementation of the intervention. Recommendations: Providing continuous training, counseling, and support for mothers is essential to maintain their participation in the management of their children with JIA. Moreover, tailored nutritional programs that address the specific needs of children with JIA are needed to maintain normal physical growth and boost immunity.