This article examines the role of private actors in the implementation of the sustainability criteria for biofuels outlined in the Renewable Energy Directive of the European Union (EU). The article demonstrates that private verifiers' participation is essential for governing greener biofuels in the EU. The article's objective is twofold. First, it analyzes the two methods for the verification of compliance with the biofuels sustainability criteria, focusing on the role of private verifiers. This analysis sheds light on an interface of public and private action that is also an opportune platform for exploring theoretical concepts. Therefore, second, the article examines the relevance of private verifiers' participation in the implementation framework for sustainable biofuels. Drawing on the concepts of European ‘new governance’ and ‘co-regulation’, the article shows that involving the private sector in the implementation of a legally binding EU Directive adds certain dynamics and constitutes modern regulatory innovation, but at the same time it makes the implementation framework more complex.