Pediatric Crohn's disease (CD) is more common today than in prior decades. Therapeutic goals in children with CD are to reduce symptomatology, promote normal growth, and avoid nutritional deficiencies. Diet plays a crucial role in the treatment of CD. However, there is a lack of comprehensive guidelines and individualized dietary approaches. A 12-and-a-half-year-old boy presented with chronic diarrhea, intermittent fever, abdominal pain, and a history of eczema. At the first visit, his body mass index (BMI) was 14.4, and his BMI-for-age was in the 1st percentile, classifying him as underweight. He received the diagnosis of Crohn's ileocolitis and gastritis and was unresponsive to treatment for 10.5 months. The patient was placed on a tailored dietary approach based on the in vitro leukocyte activation assay-MRT (LAA-MRT®), known as the Lifestyle Eating and Performance (LEAP) program. The LEAP program is an elimination diet built on the selection of less-immune-reactive foods and chemicals identified by the LAA-MRT® results. After 39 days of following the LEAP program, his fecal calprotectin levels decreased from >2000 μg/g to 185.9 μg/g. A repeat esophagogastroduodenoscopy (EGD) and colonoscopy with 10 biopsies showed complete histologic remission 1 year after beginning diet therapy. At that point, the patient discontinued his pharmacologic therapy and maintained clinical remission of CD after more than 3 years of follow-up. In addition, his anthropometric measurements and laboratory biomarkers were normalized. This case presents evidence supporting the use of the LEAP program in clinical practice as an adjunctive, tailored dietary option to manage pediatric CD.