User engagement is critical for the successful adoption and use of mobile health apps, but it is also influenced by a variety of factors that are not always easily accessible or quantified by designers in practice. The goal of this paper is to facilitate the application of activity theory and the communicative ecological framework to uncover various socio-cultural contexts for user engagement designs using the Design Process Engagement Enhancement System (DECENT) toolkit. The DECENT toolkit is an innovative theory-based design tool and associated method that includes socio-cultural filtration and a socio-cultural checklist that are augmented in the phases of the user-centered design model. This paper presents a set of consolidating concepts to guide future design practice which broaden designers’ knowledge of mobile health app designs for user engagement. Finally, to fully explain and design for user engagement in mobile health, an integrated approach incorporating a variety of technological and socio-cultural factors is presented.