AbstractDeveloping countries increasingly participate in transgovernmental networks of global regulatory governance, but they do so in different ways. This article aims to provide an explanation for this variation for two of the major emerging powers in the world economy, Brazil and China, in their transition toward more active players in the global competition regime. Distinguishing between bilateral and multilateral transgovernmental networks and examining the domestic factors conditioning the transition of their national competition agencies from rule‐takers to rule‐promoters or rule‐makers through these networks, the article makes theoretical contributions to the linkage between transgovernmentalism and the regulatory state. I argue that differing political needs and the incomplete process of regulatory state formation push domestic agencies to join transgovernmental networks, with a need for greater legitimacy steering the Brazilian regulators to multilateral networks and facilitating their transition from rule‐takers to rule‐promoters. The Chinese agencies' primary need for expertise rather than legitimacy, by contrast, led them to pursue technical assistance and cooperation via bilateral relationships. The Chinese approach has slowed its transition from rule‐taker to rule‐promoter where its norms and practices are aligned with the established powers. Such approach will further impede its transition into a global rule‐maker in areas of competition law and policy where China's preferences diverge.