This article discusses the positioning of children both as objects of economic activity as and subjects of market relations under surveillance capitalism. It looks briefly at the history of children’s engagement with the market economy from their engagement in the labour force during industrial revolution times; their disappearance from direct economic activity during the Romantic Movement; through to their emergence as both data sources and data consumers within a big data economy. It argues that this is the first time since children retreated from the paid labour force in the late 19th and early 20th centuries due to labour law reforms that their activities are of significant economic value, and that the emergence of Internet-connected toys and things for children will significantly amplify children’s position as data sources under surveillance capitalism.