Studies have shown that political underrepresentation, measured in objective terms, contributes to populist voting. However, it is unclear whether citizens who perceive that their representation is sub-optimal vote for a populist party. This study aims to fill in this gap by conducting a systematic investigation of the relationship between perceived underrepresentation and populist voting. Leveraging unique data from the 2021 RepResent Belgian Cross-Sectional Study, this study reports on three main findings: (1) individuals are significantly more likely to vote for a populist party when they feel poorly represented; (2) the association between perceived underrepresentation and populist voting is mediated by political discontent; (3) the influence of perceived underrepresented on populist voting is observed not only among those who ideologically align with populist parties but also among individuals with divergent ideologies. This study sheds new light on the relationship between political underrepresentation and populist voting by focusing on citizens’ perceptions of underrepresentation.