Having been widely acknowledged as enabling access to education, employment, leisure and social activities, transport choices are also the cause of many challenges cities face. Recognising that change is needed, planners and policymakers are considering alternative methods of planning and delivering transport. Mobility as a Service (or MaaS) is one such idea that has gained traction with academics and professionals alike. Hailed as the answer to integrating complex transport systems, MaaS has yet to be implemented at scale in urban transport systems due in part to the lack of an agreed conceptual definition, the top-down approach to implementing what is meant to be a more personalised method of accessing transport, and the lack of local promoters (in comparison to global corporations and lobbyists). This article reflects on the current barriers to defining MaaS, considers how a novel public engagement approach could be used to create local definitions that support citizen engagement, and suggests a route forward for future research.