Greenhouse gas (GHG) mitigation actions will need to be accelerated and scaled up at both national and sub-national levels in order to meet the temperature goals of the Paris Agreement. National governments can play an important role in enabling GHG mitigation actions by non-Party stakeholders (NPS), and in enhancing the interaction between national policies and NPS actions. This paper explores actions national governments could take to facilitate NPS mitigation action in two sub-sectors with large mitigation potential and where NPS play a key role in the successful implementation of mitigation activities. These sectors are renewable electricity generation and procurement in cities and Reducing Emissions from Deforestation and forest Degradation in sub-national jurisdictions. This paper outlines some institutional, regulatory, financial and technical barriers faced by NPS in implementing GHG mitigation activities in these sub-sectors and highlights some examples of national policies and measures that have allowed specific NPS to overcome these barriers. The paper also showcases examples of enabling policy frameworks at the national level that could encourage the replication of such mitigation actions by NPS. An important, common element for successful replication of mitigation activities is for national governments to facilitate co-ordination with NPS; to improve consistency between national and sub-national policies; to identify and clarify responsibilities between different actors; and to regularly review and potentially revise national policies that may unintentionally create barriers to NPS mitigation actions.