Despite the growing body of research on consumer activism, little is understood about tourists' digitally mediated boycott consumption behaviours in relation to pro-sustainability concerns. Drawing upon research grounded in political consumerism and consumer sustainability behaviour and through a constructivist grounded theory lens via a series of semi-structured interviews, this study set out to fill this gap. Two main themes emerged from the analysis of the interviews: drivers of boycott participation (including self-enhancement, perceived egregiousness, creating change, awareness and personal proximity to the boycott cause) and the barriers to boycott participation (which include counterarguments, ineffectiveness and free-riding). The findings elucidate the vital role of digitally mediated activism in contemporary ethical tourism discourses and reveal that different digital media technologies act as both information sources and mediators of boycott decision-making when it comes to targeting perceived unethical practices. Furthermore, in contrast to how tourists' boycotts are traditionally viewed, the results of this study suggest that participation in sustainability-related boycotting occurs as a process-based continuous practice instead of a one-time boycott participation. Overall, this study provides a deeper understanding of tourists' boycott behavior in the digital age and offers implications for tourism destinations and businesses subjected to boycott targets and upstream social marketing. As a result the article provides significant avenues for further research.