Many anti‐sex trafficking analyses use the term institution in a narrow meaning, comprising mainly formal‐legal political structures (public laws and governmental organizations). However, by bringing in the new institutionalism approach, it is argued that an anti‐sex trafficking institution should refer to a relatively enduring collection of rules – including also informal rules such as norms and routines – and organized practices that prescribe appropriate behaviour for any actor, public or private, combating sex trafficking. Based on a review of current research it is concluded that anti‐sex trafficking institutions in the early 21st century tend to focus on behaviour that aims at detection, prevention, protection, crisis management, consequence management, and response. Finally, reflecting different strands of the new institutionalism approach, it is argued that the design of anti‐sex trafficking institutions depends on path‐dependencies, social constructions, international institutions, and domestic politics.