Why do both economically advantaged and disadvantaged voters sometimes converge in their support for conservative parties? This study examines how subjective class consciousness mediates the relationship between economic inequality and political behaviour in South Korea. Moving beyond conventional class-voting models based on income or occupation, it conceptualises class as a relational and perceptual construct formed through social comparison. This study argues that rising inequality weakens identification with the subjective middle class, generally associated with progressive orientations, while reinforcing symbolic divisions between those who perceive themselves as upper or lower class. Using nationally representative survey data and local administrative–level (si-gun-gu) electoral returns from 2012 to 2022, the analysis finds that both subjective class identification and local inequality are significantly associated with conservative support. At the individual level, voters identifying as either the upper or lower class are more likely to support conservative parties than those identifying as the middle class. At the local administrative-unit level, higher inequality corresponds with greater conservative vote shares. These findings suggest that inequality influences political behaviour not only through material conditions but also through perceptions of social hierarchy.