["Business Strategy and the Environment, EarlyView. ", "\nABSTRACT\nSustainability is widely framed as strategic, yet its relationship with financial brand value remains contested. We explain why prior research reports divergent results by distinguishing between activity‐based ESG metrics and customer perception‐based sustainability metrics and by theorising how each activates different value‐creation mechanisms. Drawing on Signalling Theory and Brand Value Chain Theory, we develop an integrative framework in which sustainability affects financial brand value through two interrelated pathways: an investor pathway shaping brand risk and a customer pathway shaping brand returns and long‐term growth. Using a conceptual review of 40 empirical studies, we synthesise evidence on metric heterogeneity, temporal lags, threshold effects and boundary conditions (e.g., brand size, product category and sustainability maturity) that help reconcile mixed findings. To connect theory with practice, we conduct a systematic comparative evaluation of Interbrand, Brand Finance and Kantar’s brand valuation models, assessing their choice of sustainability metrics, underlying theoretical assumptions, transparency and linkage to risk, return and long‐term growth. The comparison reveals that current brand valuation models only partially reflect the mechanisms through which sustainability is theorised to create financial brand value. We conclude with implications for improving sustainability measurement in brand valuation and for advancing research on mechanism‐specific and context‐contingent effects.\n"]