PurposeThis study aims to investigate the critical role of online brand community (OBC) engagement and brand evangelism: the role of age, gender and membership number.Design/methodology/approachTo achieve the study’s objective, 303 active Facebook OBC users were surveyed. The AMOS structural equation modelling (SEM) is used to test the hypothesised model.FindingsThe results indicate that OBC engagement improves brand evangelism. Specifically, the results show that age, gender, and OBC membership number moderate the relationship between OBC engagement and brand evangelism. Interestingly, this study found that female, younger and low-OBC follower consumers more significantly contribute to nourishing brand evangelism than male, older and high-OBC follower counterparts.Originality/valueOBC engagement is validated as a key brand evangelism driver, further substantiating its role as a crucial strategic metric. Moreover, age, gender and OBC membership number as moderating factors in the association between OBC engagement and brand evangelism (word of mouth referral, brand defence and future purchases) have been verified. Although the findings suggest that improved OBC engagement contributes to evangelism, this effect transpires more significantly among female, younger and low-OBC followers than male, older and high-OBC followers.