Online brand community is an important channel for the occurrence and dissemination of electronic word-of-mouth (eWOM) communication. Building an online brand community is also a strategy for many companies in customer relationship management and marketing. In the management practice of online brand communities, it is found that consumers' eWOM engagement intentions are not high, which affects the prosperity and development of online brand communities. Therefore, it is urgent to enable practitioners and researchers to have a more comprehensive and in-depth understanding of the characteristics and research ideas of consumers' eWOM engagement intentions in online brand communities. This study aims to summarize the unique characteristics of eWOM engagement in online brand communities, which theories have been applied frequently, and provide directions and suggestions for future in-depth research on eWOM engagement intentions. This study searched the Scopus and Web of Science databases for a systematic review of studies that are highly correlated with consumers' eWOM engagement intentions. This study summarizes three unique characteristics of consumers' eWOM engagement intentions in online communities: eWOM engagement is customer engagement on a behavioral level; segmentation of user groups is necessary; and the relationship between consumers and brands plays a key role. This study finds that the most commonly used research method is quantitative research, and the most applicable theories include social identity, social exchange, social capital, psychological ownership, and organizational support theories. Researchers who want to research consumers' eWOM engagement intentions in online brand communities in the future can refer to the three directions summarized in this study: further refine and supplement the antecedents and consequences of consumers' eWOM engagement intention; consider the subdivision of consumer groups to research consumer attitudes and behavioral motivations; include consumer demographic characteristics, cultural characteristics, and external environmental influences in the research.