This paper brings an urban communication lens to bear on the geographies of platformisation in cities. It does so by drawing on three select instances of platformised materialities in Toronto and Vancouver that represent familiar contours of urban platformisation: mobility (bike and car sharing), last‐mile logistics (on‐demand delivery), and labour (gig work). These examples are worked through Aiello and Tosoni's heuristic of cities as constituting the mediums, content, and contexts of urban communication, respectively. As mediums, platformised materialities in the form of street signs designate exclusive uses of public space by mobility platforms, communicating the spatial conditions of platform urbanism. As the contents of communication, stickers and signs advertising on‐demand meal delivery available at a restaurant venue express the platform‐driven transformation of the social relations that make the delivered meal take place. And as context, broader trends of the platformisation of labour render communication by other, non‐platform‐based materialities – such as posters calling on urban gig workers to unionise – meaningful. An urban communication perspective contributes to geographical scholarship on platform urbanism by nuancing our understandings of how platforms and platform technology capital secure and sustain themselves in cities through their material communicative capacities.