The main purpose of this study is to determine the extent to which, through the performance of (indirect) normative functions and the application of principles of good governance as assessment standards, the ombudsman institution can contribute to improving the legal quality of the government while enhancing the legitimacy of the administration and the democratic system as a whole. The study is conducted from a comparative perspective, exploring the performance of the Dutch, UK, Spanish and Peruvian Ombudsmen. They are analysed with the aim to determine how far these ombudsmen, although of different types and belonging to different legal traditions, share the same values and apply similar normative standards that can be traced back to principles of good governance. The Peruvian ombudsman is examined as a case study of the institution’s evolving role in new democracies in Latin America. This reflects the wider process of the ombudsman’s hybridisation worldwide, and how its functions and assessment standards have been adapted to the evolution of the constitutional state, not least through application of the principles of good governance, which operate at the constitutional level, as a new source of legitimacy. By primarily focusing on the steering function regarding the promotion of good administration rather than the protective function of the institution, the study concludes that the ombudsman’s activities result in changed and improved public administration, which are often underappreciated in the legal literature. The legal approach to good governance provides the conceptual framework for evaluating the performance of the institution.