["International Journal of Urban and Regional Research, EarlyView. ", "\nAbstract\nThis article examines how sustainability is mobilized as a governance strategy in large‐scale urban redevelopment. Focusing on the RIVUS Mall project in Cluj‐Napoca, alongside comparative cases from Bratislava and Gdańsk, it traces how environmental objectives are translated into institutional practices, planning rationales, and financial instruments that facilitate capital accumulation and spatial transformation. Rather than treating sustainability as a normative goal, the article conceptualizes it as a flexible governance device composed of three interlinked mechanisms: material conversion, discursive‐financial mobilization, and structural embedding. These mechanisms enable speculative redevelopment while reconfiguring state–market relations around green imaginaries and investment logics. Drawing on urban political ecology and debates on the sustainability fix, the analysis shows how degraded land is revalorized, ecological narratives are leveraged for capital mobilization, and green projects are stabilized through their integration into broader territorial visions. Far from constraining market‐led urbanism, sustainability emerges as a legitimizing grammar, derisking investments, justifying intensification, and scripting urban futures. By disaggregating the sustainability fix into actionable governance mechanisms, the article contributes to critical debates on urban financialization, environmental governmentality, and the material politics of ecological planning.\n"]