<p>This study presents a systematic literature review at the intersection of social media and environmentally sustainable tourism from the tourist perspective. Drawing on a rigorous content analysis of 163 publications, we systematize and synthesize existing knowledge, identify key research gaps, and outline directions for future research. We demonstrate how user-generated social media data are employed to analyze and manage tourist flows at environmentally sustainable destinations. We further examine how contemporary research investigates the influence of social media on destination image and travelers’ behavioral intentions. In addition, we explore how social media are used to examine tourists’ perceptions, experiences, and values related to nature-based and sustainable destinations. Finally, we analyze how social media are utilized to shape tourists’ environmental mindsets. Building on these insights, we advance an integrated conceptual model illustrating how social media function as a socio-digital infrastructure shaping environmentally sustainable tourism. Our findings provide theoretical, methodological, and practical contributions while also demonstrating how social media can be leveraged by scholars and practitioners to promote environmentally sustainable tourism.</p>