The current massive spread of populist narratives online raises questions for constitutional democracies. Through the internet, populist voices have become a relevant part of the public debate and of the political arena. This issue is even harder to address due to the role of social media in governing online content. Within this framework, we underline how the regulation of content moderation can play a critical role in mitigating the strategies of populist movements without impairing political speech. Such an approach may contribute to making digital populist strategies more exposed to democratic control. The first part of this article examines the governance of the online spaces where populist movement spread their narratives. The second part focuses on the characteristics of digital populism. The third part deals with the potential constitutional paths to address digital populism. The fourth part analyses how the substantive and procedural safeguards in the process of content moderation can help to mitigate the spread of populist content and increase democratic control.