Individual variation in preferences to maintain vs. change the societal status quo can play out in the political realm by choosing leaders and policies that reinforce or undermine existing inequalities. We sought to understand which individuals are likely to defend or challenge inequality in society by exploring the neuroanatomical substrates of system justification tendencies. In two independent neuroimaging studies, we observed that larger bilateral amygdala volume was positively correlated with the tendency to believe that the existing social order was legitimate and desirable. These results held for members of advantaged and disadvantaged groups (men and women). Furthermore, individuals with larger amygdala volume were less likely to participate in subsequent protest movements. We ruled out alternative explanations in terms of attitudinal extremity and political orientation per se. Exploratory whole brain analyses suggested that system justification effects may extend to structures adjacent to the amygdala, including parts of the insula and orbitofrontal cortex. These findings suggest that the amygdala may provide a neural substrate for maintaining the status quo, and opens avenues for further investigation linking system justification and other neuroanatomical regions.