In-destination online shopping (DOS) refers to e-shopping by tourists for tangible goods in destinations. The evolving landscape of the retail industry and consumer trends are transforming the tourist shopping arena, making DOS a viable alternative or supplement to traditional tourist shopping, especially in the context of cross-border tourism. Through two studies, this research explores the emerging DOS phenomenon and examines factors leading to tourists’ DOS behavioural intentions. In Study 1, fourteen tourists with DOS experiences were interviewed to obtain preliminary insights. In Study 2, a theoretical model based on the Diffusion of Innovation Theory was tested with 319 cross-border tourists, incorporating tourist innovativeness, serendipity, transaction costs, and DOS adoption intentions. The results show that tourist innovativeness is positively associated with intentions to engage in DOS by triggering a sense of serendipity. However, certain transaction costs pose salient barriers that hinder DOS intentions. Theoretical contributions and practical implications are discussed accordingly.