We investigate experiences of disillusionment as a source of political polarization. Disillusioning experiences motivate a search for meaning, and we propose that people respond by seeking reassurance in political ideologies, reflected in political polarization. We first tested this hypothesis in the context of two major political events: the European Union (EU) membership referendum in the United Kingdom and the 2016 U.S. presidential election. In Study 1, disillusionment stemming from the EU referendum outcome led remain supporters to express more extreme political views. In Study 2, we measured political stance and disillusionment before and after the U.S. presidential election. Political polarization occurred among Clinton supporters, and this was mediated by increased disillusionment levels. In Study 3, we manipulated disillusionment and found that disillusioned participants expressed stronger support for diverging forms of political activism. Consistent with our approach, this effect was mediated by epistemic motivations. Implications regarding the effect of political polarization in society are discussed.