With this study, a high potential for the optimization of the ecosystem services of urban floodplain soils was identified. Scholz et al. (2012) named water retention, pollutant retention and carbon storage as the most important ecosystem services of active floodplain soils. Flood events can be mitigated, ecosystems and people protected from high levels of pollution and carbon storage enlarged. Especially in cities, these ecosystem services are increasingly exposed to the stressors of urbanization and climate change. Floodplains are being decimated in favor of settlement construction, with a simultaneous increase in heavy rain and flood events. So far, ecosystem services in urban floodplain soils and their processes have not been sufficiently researched. Previous studies have examined individual ecosystem services in urban floodplains focusing on strategies to improve urban planning concepts. The aim of this study is to analyze the most important ecosystem services of soils in urban floodplains combined. Based on the gained results, optimization strategies of each ecosystem service considering increasing stressors of urbanization and climate change are developed. The urban floodplain soils of the Kollau River and the Dove‐Elbe River in the City of Hamburg were investigated for this purpose. The current state of water retention, pollutant retention, and carbon storage were analyzed and controlling factors on the respective ecosystem services identified. Field and laboratory experiments were performed to improve the process understanding of (i) accumulation processes of pollutants, (ii) water balances and sources during flood events, and (iii) mineralization of organic materials in urban floodplain soils. In the Kollau area, significantly higher levels of pollutants were analyzed in the sediments of water retention ponds compared to the topsoils of the floodplains. As an example, zinc levels of 74.35 mg kg‐1 in the topsoils and 266.71 mg kg‐1 in the sediments were measured. Within the ponds, highest accumulation ...