Key actors in the multi-level governance of human rights, National Human Rights Institutions (NHRIs) are the sole independent, non-judicial bodies that assist states with the domestic implementation of international human rights provisions. Acting as a bridge between the national and international level, one of their main tasks is to provide independent human rights expertise to facilitate states’ participation in international human rights governance mechanisms, like the Universal Periodic Review (UPR) of the United Nations (UN) Human Rights Council. Whereas the formal opportunities provided for NHRIs to contribute their expertise to the Universal Periodic Review (UPR) are clearly specified by the UN, we have limited understanding of the extent to which NHRIs are able to make use of these opportunities, and the limitations they face when they seek to participate as independent actors in all the stages of the reviewing mechanism. In this paper, we shed light on the conditions under which NHRIs are capable to act as independent experts in the context of the UPR process. To do so, we propose an original framework to assess the condition for successful NHRI participation as independent experts in human rights governance mechanisms and tests this framework in the case of the UPR. Data are collected by means of an online survey and semi-structured interviews, which targeted NHRI officials in the African and Asia-Pacific region.