Ever since the Brexit referendum and Donald Trump’s presidency, populism studies have been increasingly dominated by debates around 'post-truth'. The phenomena have been understood as a ‘two-headed beast'’, while the current conditions of public communication are seen as favorable for the kind of post-truth politics which are represented by populism. Taking the argument that populist forces can establish their own relation to the production of knowledge, we turn to unexplored nexus of populism and post-truth in Slovenia, particularly the case of Janez Janša and Slovenian Democratic Party (SDS). We suggest that Janša and SDS employ the strategy of 'counterknowledge' to assert their belief in truth that is supported by alternative inquiry. The discourse analysis includes articles published on countermedia news sites Demokracija and Nova24, as well as interviews of party representatives, particularly Janša's direct statements and his Twitter account. We show that SDS counterknowledge discourse is based on two prevailing elements: anti-communist discourse focused on exclusion of minorities and anti-intellectual ‘so-called experts’ discourse. By exploring these two elements in SDS's relation to the production of knowledge, this article contributes to a more nuanced understanding of populism and its relation to post-truth, as well as brining new empirical insights into Slovenian populist politics.