In recent years, compulsive social media use has become an increasingly serious issue in the society. On the one hand, such compulsive behavior could even be viewed as a psychiatric disorder, as it may cause negative psychosocial and professional consequences (Aladwani and Almarzouqand, 2016). On the other hand, excessive involvement in social media may have a positive side—customer engagement which refers to “a customer’s behavioral manifestations that have a brand or firm focus, beyond purchase, resulting from motivational drivers” (van Doorn et al., 2010, p. 254). Of particular interest, a behavioral dimension of engagement consists of vigor or “a customer’s level of energy and mental resilience in interacting with a focal engagement object”, and interaction or “the two-way communications between a focal engagement subject and object. The latter two dimensions” (Brodie et al., 2011, p. 257). In a computer-mediated context, this behavioral dimension of customer engagement implies continuous and repeated contact via social media. However, to our knowledge, little research has addressed the relationship between compulsive social media use and customer engagement. Against this background, this study first tests an explanatory model focusing on customer engagement, compulsive social media usage, and compulsive buying. Then, the study examines the moderating role of narcissism and vanity on the model. The data is collected from an online survey with general consumer sample in the UK. On this basis, we validate the model via structural equation model. In closing, we offer a discussion of the theoretical and managerial implications.