As mobile technology continues to evolve, the new and more strategic way of communication between brands and consumers has been gained significant attention. The branded mobile app distributed directly by a brand or a company is recognized as a new effective medium to build brand engagement for the l ong run. Because of ever changing information technology as well as the role of consumers, most brands set their ultimate goals as establishing brand engagement followed by brand trust and loyalty. Despite the growing interest on branded mobile app and bra nd engagement, previous studies have been predominantly conducted by a quantitative research that results in statistical verification, thus generating a lack of users' specific and empirical reasoning. To address literature gap, this study attempts using g rounded theory which is good for the objective of reve aling specific empirical reason ing and findings. The goal of this study is to investigate users' behavioral intentions for using BMA and to examine the role of them in relation to establishing brand eng agement. Focusing on Starbucks's branded mobile app, this study derives 3 core categories throughout open, axial, and selective coding and reveals the factors which exercise significant influence on brand engagement. The findings suggest that the branded m obile app as a promising device for communication between brands and customers has to provide long term value in more synergistic ways enough to be embedded in the very intimate machine, the smartphone.