From Purpose to Proof: Sustainability Framings and Substantiation Signals in Award‐Winning Advertising (2020–2025)

ABSTRACT Drawing on signaling theory, this exploratory content analysis examines how elite advertising awards operate as institutional gatekeepers for sustainability communication. A comparative corpus of award‐winning campaigns (2020–2025; N = 83) is used to trace observable substantiation signals rather than to verify sustainability performance or audience effects. The auto‐enriched trend layer shows a visible 2025 uptick in proof cues such as operational mechanisms, traceability, and measurable impact claims; however, robustness checks indicate no statistically detectable monotonic trend and show that the pattern is sensitive to corpus composition and the 2025 endpoint. Purpose‐dominant narratives remain prevalent, and Cannes Lions SDG Grand Prix cases are used as interpretive anchors rather than confirmatory evidence. The study contributes a purpose‐to‐proof coding framework for sustainability advertising, clarifies the boundary between communication signals and verified impact, and offers governance‐oriented guidance for reducing greenwashing risk through more legible substantiation practices.