Over the past two decades, there have been calls to integrate Education for Sustainable Development (ESD) across all subjects in the primary and secondary curricula. However, researchers have argued that sustainability and mathematics education remain largely unconnected in actual classrooms. The question of what sustainable mathematics education could look like in the twenty-first century remains unanswered. There is a pressing need to rethink, re-envision mathematics teaching and learning for the twenty-first-century learning priorities. In this note, we first present a theoretical synthesis of the specialized literature on the learning and teaching of mathematics. We then attempt to contribute to this particular area by challenging the traditional boundaries of the philosophy of mathematics, followed by some thoughts on ESD in mathematics teacher education. In doing so, we seek to call attention to the need for integrating ESD into mathematics education. We hope, through our call in this note, that more researchers will be stimulated to revisit the integration of ESD into mathematics education, and, consequently, to conceptualize how, and where, efforts should be focused to integrate the aspects of ESD with mathematics teaching and learning in schools.