Climate change research and policy frequently prioritise natural science data, overlooking complex interrelationships and conflicts of interest, as well as failing to account for historical and structural inequalities. This overemphasis on ecological factors highlights the need for a more comprehensive, multidimensional approach to urban climate strategies. In response to this need, the urban climate reactor (UCR) research team aims to redefine climate fitness by expanding its purely ecological consideration by integrating social, economic, and technological matters. Climate fitness has gained traction in German-speaking ecological circles, where it is used without contextual clarifications. The term’s vague usage has opened avenues for developing a novel assessment framework incorporating the notions of coping capacity, adaptability, transformability, and eco-harmony. Identified overarching climate fitness goals include (1) safeguarding human livelihoods and biodiversity, (2) justice, equity, and intersectionality, and (3) resilient transformation of urban living spaces and holistic approaches to technology use. Drawing from an explorative literature review and expert insights, this technology assessment (TA) method aims to evaluate the compatibility of climate adaptation and mitigation measures with the goals and values of the developed climate fitness definition. A preliminary application of the climate fitness assessment framework was conducted through case studies, including photovoltaic (PV) tiles and larger-scale urban projects such as the high line park (HLP) in New York City, as part of the effort to generalise the components of the climate fitness assessment framework under the motto “climate-fit cities for all”.