In this paper, we present the view that an ontological shift to complexity thinking will be significant in the future of physical education (PE). Complexity thinking not only moves PE beyond long dominant modernist approaches but also offers the opportunity to integrate many of the postmodern perspectives that currently seek to frame PE. Four interconnected complexity commonalities, becoming, lived time, self-organisation and boundaries, are presented in an overarching frame to guide future PE developments in ways that are coherent, connected and emergent. PE is subsequently viewed as a complex phenomenon that is always in a non-linear, messy and never-ending process of becoming. Students, teachers and other stakeholders are also complex as their past, present and future experiences constantly merge in a lived time unity to create lifelong and life-wide PE journeys that are both personalised and holistic. Central to these personalised journeys is each stakeholder's ability to self-organise and influence the trajectory of their pathways. Self-organisation, however, is not a relativist 'anything goes' phenomenon but a process that takes place within a multiplicity of boundaries. While boundaries may traditionally be viewed as divisive features, complexity thinking recognises that many boundaries are flexible and enable the creation of 'boundary spaces' in which 'rich' discussions can take place to develop more coherent, connected and emergent forms of PE. Transdisciplinary Inquiry (TDI) and Ecologically Informed Practice (EIP) are presented as perspectives that can help teachers, and others, create the 'boundary spaces' in which ways to plan and introduce complexity-informed forms of PE can be explored. The paper concludes by proposing that the challenge for PE in the future will be for practitioners to develop the adaptability, openness, confidence and self-organising skills that will be needed to make the most effective use of the 'rich interactions' that these 'boundary spaces' offer.