The 2007 United Nations Declaration on the Rights of Indigenous Peoples (the Declaration) has gained increasing attention as a tool for promoting Indigenous rights. The study reported in this article contributes to the discussion about the Declaration’s effectiveness by analysing its role in advancing Indigenous peoples’ self-determination. A qualitative case study was conducted between January and February 2018 with 18 Māori activists in Aotearoa New Zealand, using a rights-based and Indigenous-based approach to form the analytical framework. Principal findings indicate that the power imbalance in Aotearoa and weak responsiveness by government to Māori rights undermine their self-determination. The Declaration can help bridge this imbalance by providing norms and standards to hold government accountable. This article also provides new scholarship on how and why Indigenous activists utilise rights-based and Indigenous-based approaches, finding that no single approach or advocacy method is used alone and that Māori deftly combine the Declaration with Indigenous methods of activism to enhance their self-determination.