The growing use of mobile technologies is spawning firms’ adoption of mobile relationship-building techniques, including via mobile apps. However, despite the rapid rise of these technologies, little remains known regarding consumers’ mobile app- (vs. desktop browser) related behaviours, and this is therefore investigated in this paper. Specifically, we explore the effect of customer engagement (CE) and customer experience (CX) on customers’ relationship quality/loyalty intention across mobile app- (vs. desktop browser)-based interactions. Using structural equation modelling, we analyse data collected from 420 customers. The results reveal a stronger positive association between CE/CX and relationship quality/loyalty intention for mobile app- (vs. desktop browser)-based interactions, revealing the former’s strategic importance. We conclude by discussing key implications that arise from our analyses.