As nature-based tourism has recognized the seriousness of environmental issues, tourists’ pro-environmental behaviors have gained the attention of scholars and practitioners. However, previous empirical studies have not considered motivational factors and destination-related constructs within the tourism context. With the data collected from nature-based tourists, the findings of this study reveal the significant association between personal values and motivations and the significant impact of anticipated positive affect on pro-environmental behavior among nature-based tourists. Also, the findings address that the impact of empathetic concern on pro-environmental behavior is moderated by a level of place attachment to a nature-based destination. •Explored the causal relationships between three aspects of personal values and two dimensions of motivations.•Confirmed tourists have experienced dual concern about helping nature while and/or after visiting a nature-based destination.•Explored the moderating role of place attachment by expanding attachment theory in the nature-based tourism context.