The call for decarbonisation has intensified, requiring solutions to ease the phasing down of fossil fuels, develop clear funding frameworks and standards, and inform decarbonisation transitions within and beyond cities’ consumption value chains, before 2050. Science can help address decarbonisation gaps in the built environment, such as by innovating low carbon designs and practices, developing decarbonisation accounting tools , synergising strategies, and optimising trade offs. These can devise city specific pathways to accelerate the attainment of net zero targets across their sectors and systems.