Pop-up parks have emerged alongside other forms of temporary urbanism as low-cost, informal, community-engaged interventions that address pressing community needs. This article examines four pop-up parks in Australian cities (Melbourne, Sydney and Perth) that reappropriated street space for pedestrians and eventually became permanent. The article charts the developmental trajectories of these four projects, drawing on local planning documents, interviews with key actors, and government and media reports on how the pop-up parks performed. It uses mapping to analyse the context of built form, activity and movement flows in and around the four sites. The study shows how these pop-up trials served as a ‘proof of concept’ for permanent spaces, tested their impacts, made community consultation more open, engaging and tangible, and increased community support. These originally temporary spaces also facilitated wider strategic urban development outcomes, emboldening local governments to further improve public space in urban intensification areas.