Citizen science, community science, and related participatory approaches to scientific research and monitoring are increasingly used by environmental educators and conservation practitioners to achieve environmental education (EE) goals. However, evidence of EE learning outcomes from these approaches are typically reported on a case-by-case basis, if at all. We undertook a systematic review of empirical studies in which community and citizen science (CCS) projects lead to EE outcomes. We surfaced 100 studies that met our inclusion criteria using a broad definition of CCS and empirical research on EE outcomes. The studies involved people in a wide variety of aspects of environmental research that included, but also went beyond, data collection. We found CCS approaches to EE overall resulted in positive learning outcomes for adults and youth, particularly gains for science content knowledge (56 articles), science inquiry skills (32), positive attitudes toward science and the environment (16), and self-efficacy toward science and the environment (11). We also found evidence for positive gains in environmental behavior and stewardship (29) and community connectedness and cooperation outcomes (30). These findings highlight how CCS programs may be uniquely impactful when involving people in planning, data analysis, and reporting aspects of environmental research and monitoring, as well as in data collection, and we offer examples and suggestions for CCS design. We found a heavy reliance on self-reporting in the research methods used in many studies, however, and so offer suggestions for more rigorous methods and directions for future research.