Michiel Leenaars combines his job at NLnet with a job as director of Internet Society Netherlands, one of the more sizable Internet Society chapters in the world. He is also a W3C liason officer for the Benelux Office of the World Wide Web Consortium.

He is also a member of the UNESCO PERSIST Technical Taskforce. PERSIST (Platform to Enhance the Sustainability of the Information Society Transglobally) is a cooperation between UNESCO, the International Council on Archives (ICA), the International Federation of Library Associations and Institutions (IFLA), LIBER, and several other organisations to collect and share worldwide best practices and guidelines on selecting policies and digital strategies.

He is active in a number of national and international organisations, such as OpenDoc Society (vice-chair), SIDN Fund (Board of Advisors), Digitale Infrastructuur Nederland, and Petities.nl foundation (treasurer).

From 2014-2018 he was member of the Netherlands national Education Council. The "Onderwijsraad" is the highest Netherlands governmental advisory body to advise the Minister, Parliament and local authorities on education policy.