Both physical activity (PA) and nature exposure are associated with several youth health benefits. However, the health outcomes when being physically active in nature, called Green Exercise (GE), are less clear. Thus, the purpose of this systematic review was to provide an overview of the psychosocial and physiological outcomes of GE in children and adolescents and to outline future GE research directions. The PRISMA statement guided the review. Web of Science, PubMed, ERIC, and APA PsychNET were systematically searched in February 2019, including studies between 2000 and 2019. Fourteen of 1175 identified publications were included, which reported 15 different psychosocial and six different physiological outcomes, with some studies reporting more than one outcome. For 16 outcomes, studies reported either similar or no effects for both GE and comparison groups. For six outcomes, studies reported stronger effects for GE, for three outcomes, studies reported stronger effects in the comparison group. Evidence was rated as weak, using the EPHPP tool. Thus, GE does not have deleterious effects for children and adolescents compared to PA in other settings. ... mehrGE might be beneficial; however, due to the study’s heterogeneity and quality, it is premature to make definite conclusions. Future research should build the quality of evidence for GE, use more rigorous research designs, and investigate the underlying effects and mechanisms of GE.