Practitioners designing for mobile learning (mLearning) and scholars exploring the same are faced with the challenge of planning for and understanding a variety of ways and places of learning. This study focuses on one crucial distinction concerning this; that of formal and informal learning. Through the analysis of contemporary research literature, we found that informal learning is represented as more enriching than formal learning. We also identified that some representations of informal learning, such as subconscious and tacit, actually gainsay the idea of designing the learning process. Based on these results we propose a number of implications to enhance pedagogical sustainability in mLearning design. We argue that in order to fuse informal and formal learning, mLearning designers need to offer more clear definitions of the concepts “formal” and “informal”; they need to omit some design aspects to the learners themselves, or to offer a design in form of a learning path that students themselves can customise according to their learning habits, routines, and preferences.