In the 2017 Czech parliamentary election, the Czech Pirate Party (Pirates) gained 10.79% of the votes – an unprecedented success, compared to most of the pirate parties across Europe. However, as their electoral gain varies widely across the Czech Republic’s territory, this article analyses all (more than 6000) Czech municipalities in the elections of 2010, 2013, and 2017 to explain this variation. Overall, the success of the Pirates was driven especially by obtaining much more support in larger municipalities with younger populations (although not only those aged 18–24 but also older ones), lower unemployment, higher turnout, and lower support for leftist parties. Thus, from a spatial perspective, the patterns of Pirate voting largely resembled long-term spatial support for Czech rightist parties and we can conclude that the Pirates made considerable inroads to regions which had historically been strongholds of the Civic Democratic Party, as the former main party of the right, but also strongholds of minor right-wing (‘liberal centre’) parties of the 1990s and early 2000s. Success of the Pirates thus was based especially on votes from municipalities located in more developed areas, where the Pirates received many more votes than in structurally disadvantaged regions.