While National Human Rights Institutions are widely regarded as particularly promising tools in the emerging transnational regime for the regulation of business and human rights, we still know little about their potential and actual contribution to this field. This article bridges the gap between business and human rights research and NHRI scholarship, proceeding in three steps: Firstly, I analyze the structural conditions for NHRIs to tackle business-related human rights abuses effectively, focusing on the key conditions of legitimacy and competences. Secondly, (...) I examine the envisaged role and functions of NHRIs in business and human rights regulation according to the Paris Principles and the UN Guiding Principles. Thirdly, I reconstruct and critically assess NHRIs’ mandates and powers to address corporate human rights abuse, based on the analysis of surveys and reports. I argue that there is a significant mismatch between the essential structural conditions for effective NHRI engagement with business and human rights, the expected contribution of NHRIs to the prevention and remedy of corporate human rights abuses, and the limitations of their mandates and powers in practice. To overcome that misalignment and unlock NHRIs’ full potential, this article proposes a reform of the Paris Principles which would provide these institutions with a robust source of international legitimacy and increase the pressure on state governments to extend their powers. (shrink)