•Children with Juvenile Idiopathic Arthritis (JIA) have a guarded, crouched gait.•Ankle power, leg joint sagittal plane excursion and joint loading are reduced in JIA.•Exercise and/or pharmaceutical interventions may improve JIA gait features. Juvenile Idiopathic Arthritis (JIA) is a chronic inflammatory arthritis that impacts biomechanical features of gait. This systematic review describes the effects of JIA on gait motion parameters and walking performance. Six databases were searched (PubMed/Medline, Cochrane, the EBSCOHost database SPORTDiscus, Web of Science, and Embase). Studies were restricted to children with any subtype of JIA who were assessed for gait motion features (kinematic, kinetic, temporalspatial) or walking performance (velocity or distance covered); could include intervention or treatment exposure with measures of gait and gait speed; could involve comparison of gait in JIA to healthy controls. Quality of evidence was assessed using the GRADE system. This systematic review was registered at PROSPERO (CRD42018109582) The search yielded 625 papers, 23 of which described biomechanical features of gait and/or assessed walking performance. Twenty studies measured walking velocity and walking ability using simple field tests or laboratory methods. Eleven studies measured temporalspatial parameters such as cadence, step length, stride length, step width, single and double support time. Nine studies evaluated kinetic measurements including joint power, flexion and extension and joint moments. Nine studies evaluated kinematic parameters including range of motion, pelvic tilt, center of motion and trunk sway. Key features of gait in children with JIA include slower gait velocity, shortened step length, decreased range of motion at the hip, knee and ankle with trend towards flexion, decreased joint power, anteriorly tilted pelvis and trunk with shifted center of motion. There is a potential to ameliorate JIA-related gait changes with exercise and/or pharmaceutical interventions.