Purpose: The purpose of this umbrella review was to summarize and evaluate the available evidence concerning risk factors for early childhood caries (ECC). Methods: Literature searches were performed until July 2020 in Medline, Web of Science, and EMBASE databases. Systematic reviews were selected, and their methodological qualities were assessed using the AMSTAR 2 tool (16 items). Results: A total of 977 articles for possible inclusion were identified, and 15 studies were finally selected for qualitative analysis. In these 15 studies, the risk of bias varied from critically low to high. The included studies reported risk factors for ECC such as dietary factors, mutans streptococci, low maternal education, maternal age, low family income and parental education level, low social class, enamel defects, obesity, the presence of dentinal caries, presence of Candida albicans, moderate to late preterm birth, and prenatal maternal cigarette smoking. Conclusions: The potential risk factors for early childhood caries are enamel defects, high levels of mutans streptococci, the presence of dentinal caries, increased consumption of soda, daily intake of sugary snacks, and obesity. In the future, longitudinal studies are needed to explore the potential relationship between these risk factors and ECC.