The voluntary/mandatory divide is a constant feature of scholarly debates on corporate accountability for sustainability in global supply chains. A widely held assumption is that the addition of state authority to private transnational governance in global supply chains will “harden” accountability and, thus, promote more sustainable production. The state's ability to set legally binding requirements is expected to coerce companies into complying. The hybridization of private and state authority is seen to strengthen good practice in private authority. This empirical study questions these assumptions based on an analysis of two hybrid governance arrangements for sustainability in global supply chains: the EU's Timber Regulation (EUTR) and Renewable Energy Directive (RED). The results demonstrate that both EUTR and EU-RED yield sector wide efforts of compliance and to this extent can be seen as enhancing accountability in the sense of answerability. At the same time, we find that the policies in both cases are not more demanding, nor enforced strictly, the latter putting into question their potential to coerce companies. Further, a “hardening” of accountability is at least obscured as both EUTR and EU-RED have stripped private authority they employ in their hybrid transnational governance from the need to establish legitimacy with a broader audience. This makes legal compliance and cost-effectiveness the core factor for companies’ efforts to demonstrate compliance. Our findings hence question whether the EUTR and EU-RED have led to “hardened” accountability compared to private transnational governance, and ask for an empirical, more nuanced understanding of what there is to gain or lose from hybridizing private and state authority in transnational governance.