Purpose: To examine safety and efficacy of exercise training (ET) for juvenile idiopathic arthritis (JIA) to improve physical fitness, pain, functional capability, and quality of life. Methods: Ovid Medline, PubMed, CINAHL, PEDro, and Web of Science were searched from 1995 to April 2018 to find English-language articles examining effects of ET in JIA, ages 4 to 21 years. Quality of evidence/strength of clinical recommendations were assessed using the Cochrane GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system. Results were reported using the 2009 Preferred Reporting Items for Systematic Reviews and meta-Analyses (PRISMA) checklist for health care interventions. Results: Nine papers met inclusion criteria. A total of 457 individuals with JIA, ages 4 to 19.9 years, received ET or alternate activity, wait-list, or no intervention. Moderate-quality evidence supports Stott Pilates and underwater knee-resistance exercise. No adverse effects of ET were reported. Conclusions: Moderate-quality evidence exists for ET (30-50 minutes, 2-3 times/week, 12-24 weeks) to decrease pain, improve range of motion, knee strength, functional capability, and quality of life in JIA.