Background: Denialism of coronavirus disease 2019 (COVID-19) severely affected governments’ attempts to contain the spread of the virus. Indeed, groups of deniers showed scepticism and misinformation toward the causes of the virus, leading to less adherence to official guidelines and vaccination campaigns. The present study aimed to investigate the sociodemographic and psychological factors associated with COVID-19 denialism, expressed in the forms of scepticism, nonadherence to guidelines, and negative attitudes toward vaccination. Methods: Four hundred and sixty-one volunteers completed an online survey composed of the Beck Hopelessness Scale, the Dissociative Experiences Scale-II, the Sense of Community Index, and a questionnaire about COVID-19 denialism. Results: The multiple regression analyses showed that higher age and a lower level of education were positive predictors of COVID-19 denialism. Furthermore, the structural equation model showed that hopelessness positively predicted dissociation and negatively predicted the sense of community. In turn, only dissociation was found to positively predict COVID-19 denialism. Conclusions: The findings of the present study suggested that hopelessness could exacerbate a defensive dissociative response that could be associated with greater COVID-19 denialism. Moreover, older and less educated people showed a greater propensity to engage in COVID-19 denialism.