International migrants are subject to many types of violence, such as trafficking, detention, and forced labour. We need an improved understanding of what protects migrants from such violence. The concept of ‘migrant protection regimes’ draws our attention away from formal rights advocacy and to both the informal dimensions of protection and the way migrants help determine the quality of protection they receive. ‘Migrant protection regimes’ are sets of rules and practices regarding who ought to protect whom. These regimes include formal rights to protection in the law and informal relationships that protect migrants from lawful violence by the state. They may be changed by ‘power grabs’, when sovereign actors seek to monopolise protection relationships, but also by ‘exits’, when migrants refuse to accept the protection on offer. The study demonstrates the value of these concepts by using them to explain an unlikely case: a change in laws concerning migrant protection in an authoritarian state: Thailand. Drawing on rich qualitative sources, the article reveals how, after a human rights advocacy campaign had placed migrants’ protection in jeopardy, a mass migrant exodus compelled the country's junta to offer migrants protection on better terms.