Complex multi-stakeholders and multi-level governance structures have emerged in areas that were traditionally exclusive to state and treaty-making. The adoption of the United Nations Guiding Principles on Business and Human Rights (UNGP) affirmed a corporate responsibility to respect human rights to be implemented through human rights due diligence (HRDD), that is, through management processes. This contribution conceptualizes the UNGP from the perspective of regulation as a principled exercise in polycentric governance dependent on regulatory intermediaries for interpretation. It then assesses the role of various sui generis normative instruments in interpreting the UNGP and how the presence of an additional layer of interpretive material contributes to the institutionalization of responsible business conduct. The analysis of instruments developed by international, non-governmental and business organizations reveals both a decentralizing tension between different intermediaries due to disagreements over the exact extent of corporate human rights responsibilities, as well as attempts to centralize the UNDP's interpretation. The article concludes by recommending caution regarding the use of polycentric governance regimes and their lack of centralized interpretive authority in this domain of international law, and suggests possible ways to formally establish centralized interpretation