Background: Social media (SM) have become the integral part of consumers’ daily life, prompting multidisciplinary research on their link with human behaviors, including food attitude and consumption. However, the precise role of SM in shaping food consumer behavior remains partially explored. Scope and approach: This review adopts a systematic literature approach, focusing on the methodological and outcome characteristics. Applying PRISMA guidelines, 377 studies were identified and categorized into three SM functions: Tool, Determinant, and Source. Tool studies involved active SM use for research, while Determinant studies measured SM-related variables' impact on outcomes, and Source studies involved data extraction and analysis from SM. This review traces the growth of studies over time, highlighting the study characteristics focusing on the methodology, and the scope of the findings per function. Key findings and conclusion: Data collection methods differed across functions: Source studies relying on user-generated content (UGC) via data mining, other functions mostly employed surveys targeted to participants. Notable platforms include Facebook (Tool) and Twitter (Source), with cross-sectional designs being prevalent. Tool and Determinant studies linked SM with food intention and behavior, Source studies delved into categorization and exploration of UGC and consumers’ sentiments related to food. In both the Tool and Determinant functions, most studies demonstrated the influence of SM on outcome measures. As each function has its own distinct characteristics, knowledge from all functions should be considered to gain comprehensive perspective regarding the relationship between SM and food consumer behavior.