Trust between constituent actors within the European Union (EU)’s multilevel regulatory regimes is decisive for regulatory success. Trust drives information flows, increases compliance, and improves cooperation within these regimes. Despite its importance, systematic knowledge regarding the drivers of trust within regulatory regimes is limited. This paper inquires whether trust in regulatory agencies is influenced by their affiliation with the national or EU governmental level, as well as by their performance. While existing literature predominantly focuses on why citizens place their trust in governments or regulatory agencies, this paper presents original insights regarding the formation of trust among elites within the regulatory regime, including politicians, ministerial officials, agency officials, interest groups, and regulated entities. We employ data obtained from a large-scale vignette experiment conducted in six countries involving 752 decision-makers from relevant organizations. The experimental results suggest that both public and private elite actors’ trust assessment of regulatory agencies does not hinge on cues associated with the governmental level, but rather depends on agency performance. Accordingly, belonging to the national or EU governmental level does not create a difference in trust assessment of regulatory agencies in itself. It, however, shows that particularly elite actors are rather sensitive in terms of the performance of a regulatory agency.