Abstract: Knowledge about how marginalised citizens use urban spaces is hard to access and apply in urban planning and policy. Based on current debates around “smart cities” and “smart governance,” the City of Odense, in Denmark, has tested the integration of “smart engagement” by means of GPS-tracking techniques into the municipality’s cross-sectoral strategy for an “inclusive city.” In a period of austerity, cities have the incentive to optimise public services. Hence, GPS-tracking data was produced by 64 marginalised citizens, resulting in a data inventory covering three weeks of spatial behaviour. First, this article shows how these GPS-tracking data were processed into maps without revealing person-sensitive spatial patterns. Secondly, the article explores whether such maps and the GPS-tracking techniques that underpin them are considered valid, relevant, and applicable to urban planning from the perspectives of marginalised citizens, their representatives, and municipal planners and professionals respectively. The GPS project showed shortcomings as regards the quality of the data inventory and the representativity of the mapped behaviour, which made them inapplicable for optimising dedicated public service. However, the article also finds that the GPS-based maps succeeded in being non-person sensitive and in providing a valuable platform for citizen-centric dialogues with marginalised citizens with the potential for raising awareness and increasing knowledge about this citizen group’s living conditions and urban lives. An important derived effect of the project is that it has ensured ongoing cross-sectoral collaboration among a range of professional stakeholders, imperative for ensuring creating greater equity in urban planning.