During the last decade, many cities worldwide have implemented various green policies; in this way, they have gradually transformed into “green cities”. The emergence of green cities may provide a promising venue to address cities’ environmental degradation and citizens’ disengagement with current socio-environmental issues, thus giving rise to the notion of Environmental Citizenship (EC). Despite these assumptions, empirical research on the topic is currently emerging. In this study, we examine citizens’ engagement in green cities and its interrelatedness with EC through a systematic literature review. The selected empirical studies (n = 25) were published in peer-reviewed journals during the timespan of the last 12 years (2010–2021). In total, 31 green cities were analyzed in the 25 selected empirical studies. Thematic and frequency analysis revealed that green cities encourage citizens’ engagement with the implemented green policies, while also advancing citizens’ EC. Furthermore, correlational analysis between citizens’ engagement and the Education for Environmental Citizenship (EEC) model revealed that citizens’ engagement with the implemented green policies fosters citizens’ knowledge, skills, attitudes, values, and behaviors, fueling the undertaking of various EC actions. Importantly, green cities have also proved successful in achieving EC’s outcomes leading to sustainability.