This study critically examines sustainable development (SD) within the contemporary practices of city branding, a prominent business philosophy that underpins market-led development strategies of urban areas. In pursuing uniqueness, different cities often seem to hint at the very same themes of differentiation, and this reflects the tendency to embrace pre-given sets of place-development discourses. This work casts a critical perspective on SD as one of the global passe-partout themes that has become particularly prominent in contemporary city-brand management practices. In particular, the theory-practice gap in city branding for SD is emphasized and interpreted through the lens of glocalization theories. This viewpoint identifies responsibilized boundary spanners as agents located between the global and local levels that act as mediators in multi-stakeholder networks, ultimately fostering capacities to implement collective actions in city-branding practices.