Delta cities are exposed to cycles of fluvial risks that have been managed across space and time. Floods and flood mitigation in urban deltascapes are therefore dependent on territorial and historicised dynamics. This paper uses historical urban political ecology to unravel the changing interactions between biophysical and political-economic processes affecting urban deltascapes in particular periods from the sixteenth century onwards. We present two case studies: Arles (on the Rhône Delta, France) and Kolkata (on the Bengal Delta, India). Our empirical findings point to the influence of connected global processes and to similarities in historical trajectories. In particular, both case studies reveal state efforts to ‘fix’ the fluid deltascape originally managed by local institutions, altered flood vulnerabilities (in terms of frequency, intensity and space), and more recent initiatives of mediation between interest groups. Through this unexpected comparison, more generally, we aim to contribute to a (global) environmental history that is sensitive both to local specificities and complexities and to the influence of global processes.