The use of mobile learning, or M-learning, has been increasingly appreciated by educators due to its sustainability potential in different facets such as finance (i.e., affordable cost) and flexibility (i.e., time and pace of learning). However, it may not be effective in all situations. This study explored the feasibility of using M-learning for students’ self-study of mathematics in the context of Vietnamese high schools. Using 542 student and 40 teacher responses to two surveys, the study showed that the use of M-learning might not be feasible for students’ self-study of mathematics due to difficulties related to accessing mathematics websites, the quality of mathematics website content, students’ low level of self-learning ability and learning disengagement. This study suggests that the use of M-learning may contribute to the sustainability of education; adopting it should be based on a critical examination of contextual factors, especially students’ self-learning ability and engagement. M-learning can be promising and beneficial to students due to its capability to equip students to prepare for the fast-changing and technological-driven world. Educators have increasingly appreciated the use of M-learning, because it becomes more affordable and flexible. Nonetheless, there is still a question about near-future adoptions of M-learning due to unavailability of and inaccessibility to quality contents from trusted maths websites. The propensity of student engagements in M-learning is also an important issue for future research.