This article traces the journey of France towards an institutionalization of parliamentary ethics. Since the 1980s, French parliamentarians have adopted a series of laws creating institutions and instruments to control their finances and regulate their conduct, most often in reaction to political scandals. This case study is based on the analysis of parliamentary archives, administrative documents and semi-structured interviews with actors involved in the regulation of parliamentary ethics. The article shows that parliamentary ethics in France has been transformed over the last thirty years, from a prohibition-based regime focusing on a priori bans and wealth control to a regulatory regime introducing disclosure obligations and ethical counsel. Parliamentary ethics regulation in France also evolved from a system of self-regulation to a system of co-regulation, with the creation of several oversight institutions and a move towards further externalization since the 2010s. The multiplication of oversight institutions and mechanisms, while strengthening control over parliamentarians’ conduct, however resulted in the fragmentation of parliamentary ethics oversight, rendering the system overly complex. Lastly, the article argues that, while the French parliamentary ethics regime remains largely compliance-based, relatively few parliamentarians have actually been sanctioned for ethical violations.