Conspiracy Beliefs (CB) are a key vector of violent extremism, radicalism and unconventional political events (e.g. Brexit). So far, social-psychological research has extensively documented how cognitive, emotional and intergroup factors can promote CB. Evidence also suggests that adherence to CB moves along social class lines: low-income and low-education are among the most robust predictors of CB (Uscinski, 2020; van Prooijen, 2017). Yet, the potential role of precarity – the subjective experience of permanent insecurity stemming from objective material strain – in shaping CB remains largely unexplored. In this paper, we propose for the first time a socio-functional model of CB. We test the hypothesis that precarity could foster increased CB because it undermines trust in government and the broader political “elites”. Data from the World Value Survey (n = 21,650; Study 1, electoral CB) and from representative samples from polls conducted in France (n = 1760, Study 2a, conspiracy mentality) and Italy (n = 2196, Study 2b, COVID-19 CB), corroborate a mediation model whereby precarity is directly and indirectly associated with lower trust in authorities and higher CB. In addition, these links are robust to adjustment on income, self-reported SES and education. Considering precarity allows for a truly social psychological understanding of CB as the by-product of structural issues (e.g. growing inequalities). Results from our socio-functional model suggest that implementing solutions at the socio-economic level could prove efficient in fighting CB.