Objective: Observed disparities in health behaviors and outcomes may be associated with socio-structural variables and individuals’ beliefs concerning health behaviors. We proposed and tested a model in which the effects of health literacy, an independent predictor, on two target outcomes, health behavior participation and health-related outcomes, were mediated by belief-based constructs from social cognition theories. Method: Studies (k = 203, N = 210,622) reporting relations between health literacy, social cognition constructs (attitudes, self-efficacy, knowledge, risk perceptions), and health behaviors and outcomes were identified in a systematic database search. Relations among proposed model variables, including indirect effects of health literacy on health behavior and outcomes mediated by social cognition constructs, were tested using random effects multilevel meta-analysis and meta-analytic structural equation modeling. Results: The analysis revealed nonzero averaged correlations between health literacy, social cognition constructs, and health behavior and outcomes with small-to-medium effect sizes. Structural equation modeling indicated that self-efficacy and attitudes partially mediated the relationship between health literacy and health behavior and outcomes. Sensitivity analyses revealed that model effects did not vary substantively when omitting studies targeting health-risk behavior, studies using comprehension measures of health literacy, and studies in countries with high education provision. Conclusion: Findings indicate that relations between health literacy and health behavior and outcomes are partly accounted for by health behavior beliefs suggesting a potential mechanism by which health literacy may relate to health behavior and outcomes. Given these findings are based on correlational data, further corroboration is needed in studies adopting longitudinal or experimental designs.