Cognitive–behavioural and metacognitive approaches to emotional disorder implicate beliefs in social anxiety, but the types of beliefs differ across these perspectives. Cognitive models suggest that social beliefs about the self (i.e., high standards and conditional and unconditional beliefs) are central. In contrast, the metacognitive model gives centre stage to metacognitive beliefs (i.e., positive and negative beliefs about thinking) as main contributors to the maintenance of the disorder. Despite an expanding research interest in this area, the evidence for such contributions has not yet been reviewed. This study set out to systematically review relevant cross‐sectional, longitudinal, and experimental investigations of the direct and indirect (through cognitive processes, such as anticipatory processing, self‐focused attention, the post‐mortem, and avoidance) relationships of social and metacognitive beliefs with social anxiety. Clinical and nonclinical samples were included, and correlation and regression coefficients as well as results from group comparisons (e.g., t tests and analyses of variance) were extracted. Overall, 23 papers were located, through PsycINFO, PubMed, and Web of Science, and reviewed using narrative synthesis. The results showed a robust positive relationship between social beliefs and social anxiety that appeared to be mediated by cognitive processes. Specific metacognitive beliefs were found to positively contribute to social anxiety both directly and indirectly, through cognitive processes. The study's findings are limited to 2 models of social anxiety and other minor limitations (e.g., grey literature was excluded). With these accounted for, the results are discussed in terms of the conceptualization and treatment of social anxiety and suggestions for future research are made. KEY PRACTITIONERS MESSAGES High standards and conditional and unconditional beliefs positively and significantly correlated with social anxiety. These relationships appeared to be affected by cognitive processes, such as anticipatory processing, self‐focused attention, and post‐mortem processing. Positive and negative metacognitive beliefs and beliefs about the need to control thoughts positively and significantly correlated with social anxiety. Metacognitive beliefs showed both direct and indirect (via cognitive processes) effects on social anxiety. The general methodological quality of the papers was moderate to very good.