PurposeThe purpose of this paper is to examine the non-linear effects of work engagement (WE) on the job outcomes’ creative performance (CRP), extra-role customer service (ERCS) and turnover intention (TI).Design/methodology/approachData were collected from 405 millennial frontline employees (FLEs) working in the hospitality industry in Kenya. Structural equation modeling was used to examine the hypothesized relationships.FindingsThe results yielded support for one relationship. WE was found to have a significant non-linear relationship with TI. This finding provides evidence of a ceiling to the positive impact of WE on reduced TI. WE and CRP and ERCS were however found to be non-significant and linear, and significant and linear, respectively.Research limitations/implicationsA large number of studies have evidenced positive individual and organizational outcomes associated with WE. This study however, is important, as the “dark side” of WE is empirically examined, therefore providing a different perspective of the concept.Practical implicationsThe study findings affirm that management must exercise caution with excess levels of WE among millennial FLEs as this may lead to unfavourable outcomes.Originality/valueIn this research, the assumption of linearity is challenged. Empirical evidence for the need to systematically explore non-linear associations for a more nuanced understanding of the relationships between variables is provided. Moreover, this study is among the few in which the presence of curvilinear relations between WE and job outcomes is examined in a non-Western context.