The Lisbon Treaty and the Charter of Fundamental Rights acknowledge the right to “good administration” as a fundamental right of EU citizens. This has led to the reinterpretation of the mandate of the European Ombudsman, as it has actively sought to extend its competencies to promote good governance, instead of solely investigating possible acts of illegality. This proactive work has also involved own-initiative inquiries and strategic initiatives that have particularly targeted transparency of EU governance and conflicts of interest. This had led to institutional tensions and the politicization of the Ombudsman’s work and mandate through high-profile cases. As a supranational institution of accountability, the European Ombudsman is a unique interpretation of a global institutional model, showing both its potential and limitations. This is now reflected in the institutional debates about the mandate of the European Ombudsman.