While previous works have extensively studied how authoritarian governments use state violence to suppress political expression and deter collective action, little is known about the effect of violence and its effects in democratic countries. Does the experience of state repression polarize views against the democratic regime? Does it foster or suppress political participation? Who is more likely to be affected? We address these questions by exploring the impact of police violence during the 2017 Catalan independence referendum on the subsequent regional election scheduled two months later. Leveraging panel data on election results from the 2012, 2015 and 2017 elections and distance to the police headquarter as an instrumental variable, we examine whether violent interventions by the Spanish police during the independence referendum affected turnout and pro-independence support. In addition, we delve into the mechanism and exploit an original survey conducted in several polling stations, half of them ‘treated’ with police violence during the Election Day. Overall, we find that violence increased the relative share of the votes received by pro-independence parties, although the effect is driven by a higher propensity to abstain among unionist voters. Results shed light on the impact of state violence on political polarization and mass political participation.