Augmented reality (AR) is gaining attention as one of the methods for realizing metaverse experiences. Although previous studies identified authenticity and narrative transportation as positive predictors of tourist behaviors in AR tourism, few studies have explained why authenticity and narrative transportation can affect tourist behaviors in AR tourism. To fill the research gap, drawing upon attachment theory, this study aims to examine the mediating role of AR attachment between authenticity, narrative transportation, and word of mouth. Through structural equation modeling analysis, the findings indicated AR attachment mediated authenticity, narrative transportation, and word of mouth. This study advanced attachment theory by proposing a new concept, AR attachment, and tested its mediation effect. Furthermore, the findings are beneficial for heritage tourism managers to understand AR heritage tourism marketing.