In this article, we analyse how anti-globalist conspiracy theories were mobilised online to delegitimise national authorities and policies designed to curb the Covid-19 pandemic in Canada. These conspiracy theories attacked the political authority underpinning public health measures and targeted purportedly ‘liberal’ policies and ‘globalist’ actors. Our case study examines the Freedom Convoy, a series of protests against Covid-19 vaccine mandates that began in Canada but inspired global demonstrations. The Freedom Convoy fostered and relied upon anti-globalist conspiracy theories, including the ‘Great Reset’ and ‘Great Replacement’, both of which posit a global conspiracy to erode national sovereignty and impose a ‘liberal’ international order. We investigate far-right social media commentary from 4chan’s Politically Incorrect imageboard /pol/, Infowars, and Rebel News, showing how conspiratorial claims were marshalled in alt-tech spaces. These narratives were used to delegitimise public health measures to combat Covid-19 and the Liberal Trudeau government by linking them to various ‘globalist’ forces. In exploring three mechanisms of delegitimation – externalisation, personification, and Othering – we argue that far-right movements like the Freedom Convoy, motivated by anti-globalist conspiracism, mobilise the international realm by leveraging the legitimacy gap of international organisations and agendas to undermine the political authority of actors at the national level.