How do international organisations (IOs) legitimise their right to rule in times of a Pandemic? Where are their previously made environmental commitments on their agenda during a crisis? What are the differences in self-legitimation, if any, across different types of IOs? These questions have gathered renewed urgency during the ongoing COVID-19 and climate change crises posing a threat to the legitimacy not only of national governments but also of IOs. The paper aims to address these questions through the analysis of environmental commitments made in legal documents of three IOs (the EU, the EAEU, and the AIIB) and through the analysis of their respective social media between 2017 and 2021. Among other issues, we find significant differences in self-legitimation strategies of these three IOs as reflected by their social media and some evidence of mimicry across these IOs that should remain on the agenda for further studies.