This research explored the association between authenticity and work engagement within the customer service context of mass-service industries. Authenticity in customer service workers is usually considered detrimental to organisational aims for a consistent standard of good service. However, research which finds that acting the service-persona is associated with emotional exhaustion and cynicism in workers (Brotheridge & Lee, 2002), while authenticity is related to positive customer-outcomes (Bujisic, Wu, Mattila, & Bilgihan, 2014), suggests that authenticity may enhance the experience of service for workers, and their customers, to provide for sustained competitive advantage. In the present research, I sought to examine the relationship between the degree of authenticity that employees use in their interaction with customers, and their experience of work engagement. Mass-service refers to a sector of the service industry modelled on mass-production. Contrary to principles for work engagement, workers in customer service roles within mass-service, usually repeat a small range of tasks with very little variation or autonomy. One hundred and forty service employees in petrol stations, fast food outlets, supermarkets, and in general retail responded to a survey measuring the extent to which they felt authentic, used surface acting and deep acting, their state of self-efficacy, feelings of personal accomplishment, and work engagement. Results revealed a positive relationship between authenticity and work engagement. Surface acting emerged as a less authentic approach to service than deep acting, however, deep acting was not strongly related to authenticity. Personal accomplishment strongly moderated associations with work engagement. Overall, results suggest that an authentic approach to interaction with customers and a sense of personal accomplishment are important to work engagement in mass-service workers. Findings support the promotion of authenticity in the workplace, as well as providing opportunities for workers to obtain a sense of accomplishment. Practical implications for the integration of authenticity into the customer service context, such as greater job autonomy and training customer service employees in the beneficial use of personality within the service-role, are discussed.