Voter profiling, microtargeting, and digital advertising architecture are widely recognised as threats to privacy and democratic processes. However, accounts of what voter privacy is, why it matters, and how it is threatened by new and emergent campaigning practices vary. This article examines voter privacy and its value in the context of data-driven political campaigning. In privacy theory and law, the role of privacy in political processes has predominantly been conceived as sheltering autonomous individuals from the conforming pressures of collective life and the chilling effects of surveillance. The dominant paradigms offer an inadequate explanation of the value of voter privacy in the contemporary social and technological milieu. This article argues that voter privacy is indispensable to free and informed democratic decision-making. Beyond merely enabling separation and differentiation from the collective, privacy is essential to the social and collective aspects of democratic decision-making. By reducing voter privacy, data-driven political campaigning practices disrupt voters’ abilities to self-articulate preferences, views, and affinities, to produce and circulate ideas, and to collectively deliberate and scrutinise. This conception offers an explanation of the societal value of voter privacy which can inform coherent legislative responses to the issues presented by data-driven political campaigning.