This study systematically reviewed 46 studies on adolescent digital citizenship searched by November 2022 and synthesized that (a) the predictors of adolescents' levels of digital citizenship include demographic (e.g., gender and computer use experience), individual (e.g., social networking use and Internet skills) and psychological (e.g., Internet self-efficacy and Internet attitudes) factors, and (b) digital citizenship (including digital citizenship levels and education) influences students' online behaviour and learning such as English writing performance and subject knowledge acquisition. A subsequent meta-analysis of the effect of each predictor on adolescent digital citizenship showed that Internet self-efficacy was the strongest predictor of digital citizenship levels, followed by computer self-efficacy, social media experience and Internet skills, while the effect of digital citizenship education revealed a small to moderate effect on reducing negative online behaviour. Implications for future research on digital citizenship and educational programmes for digital citizenship are discussed.