Conspiracy theories, political polarisation and anti-government sentiment have proliferated in recent years. Similarly, trust in institutions is eroding, and forms of conspiracy-fuelled violence are now more widespread. While our understanding of how and why people come to believe in conspiracy theories is well developed, the consequences of such beliefs—particularly their link to violent extremism—is less well understood. We know little about why conspiracy beliefs might drive violent extremism, and what can be done to mitigate this risk. Using Australian survey data (N = 1595)—a country where anti-government sentiment has increased significantly in recent years—our paper tests whether conspiracy believers are more likely to also endorse and engage in anti-government violence. We measure anti-government violence as (1) support for violent insurrection, (2) violent intentions toward government, and (3) self-reported engagement in anti-government violence. Our findings show a positive association between conspiracy beliefs and violence, with this relationship mediated by anger and perceived government illegitimacy. Findings also show that procedural justice mitigates anger and illegitimacy (i.e. the drivers of violence), and does so for both conspiracy believers and non-believers. Our findings suggest that governments wishing to mitigate the drivers of conspiracy-fuelled violent extremism must commit to procedurally just governance.