Ideological connections between the state, political systems and industrial relations have long been important. But the influence of the structural nature of a country's political system on trade union membership, coverage and influence has been largely overlooked. We uniquely theorize three channels through which a political system can shape unionization in the workplace independent of ideology: incentives for inclusionary governance, legislative body composition and policy enactment. Empirically, we use multiple European datasets to test the relationship between political and employee representation using multivariate analyses across more than 25 countries. We find that increased political representativeness, measured by lower disproportionality and the presence of multiparty coalitions, is a statistically significant predictor of a greater likelihood of individual trade union membership, coverage and influence, while competitive fragmentation, measured by greater numbers of political parties, is associated with weakened collective voice.