This article replicates and extends previous results indicating that system justification, in a pool of non‐American samples, decreases at the extremes of the political continuum. Data came from 29 European countries enrolled in nine rounds of the European Social Survey from 2002 to 2018. Results indicated that right‐wingers were more likely to support the existing social system than left‐wingers. However, a significant and negative quadratic effect emerged indicating that system justification decreased among extremists in both left and right‐leaning poles. Findings also revealed that the level of national populist voting moderated the relationship between political orientation and system justification so that the difference between extreme leftists and extreme rightists was further reduced when national populist voting was higher. Results seem to confirm that extremists can be critical of the existing social system and that this trend is affected by the level of the rise in populism in those countries. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement.