In Europe and the US, regional inequalities have been linked to growing electoral support for right-wing populist parties. In contrast, Japan's rapidly shrinking rural areas have continued to support the ruling Liberal Democratic Party (LDP). This makes Japan a productive case to investigate factors that moderate the electoral effects of regional decline. This paper analyzes municipal-level electoral data across four general elections between 2012 and 2021 to investigate the relationship between regional decline, interregional redistribution, and electoral behavior in Japan. We focus on municipalities designated as “rapidly depopulating”, which display above-average levels of population decline and economic dependency, based on which they receive additional government support. “Depopulating municipalities” feature stronger support for the LDP-led coalition and higher turnout. This electoral profile is most pronounced in “depopulating municipalities” that remained intact during a wave of municipal mergers in the mid-2000s. The results suggest that the combined effects of high aging rates, interregional redistribution and relatively stable socio-spatial boundaries affect electoral behavior in declining regions in ways that can benefit the established conservative party.