This article shows that an orientation towards shareholder value and corporate indebtedness at non-financial firms have been negatively associated with union density in the EU over the past 21 years. We argue that the financialisation of non-financial firms makes them prioritise their ‘external (economic) balance’ at the expense of a cooperative ‘internal equilibrium’ model. In other words, corporate financialisation pushes non-financial firms to shift to non-participatory, market-based HR systems that directly undermine the role of trade unions. This study examines this corporate financialisation-induced shift within the EU in the wake of deeper economic integration since 1999 and provides panel data econometric evidence that it has significantly undermined union membership.