PurposeGuided by the cognitive-affective system theory of personality (CAPS), this study aims to investigate the parallel mediating effects of cognitive and affective cynicism on the relationship between illegitimate tasks and employees’ adaptive performance. It also proposes growth need strength as a moderating variable for relationships between illegitimate tasks and employees’ adaptive performance.Design/methodology/approachUsing a time-lagged design, data were gathered from 330 frontline hotel employees in China.FindingsThe authors found that the presence of illegitimate tasks is negatively associated with employees’ adaptive performance, this relationship being mediated by cognitive and affective cynicism. Growth need strength weakens the negative impacts of cognitive and affective cynicism on employees’ adaptive performance. In addition, the indirect effect of illegitimate tasks on employees’ adaptive performance via cognitive and affective cynicism is stronger for employees with lower levels of growth need strength.Practical implicationsHotel managers must heed the negative impact of illegitimate tasks. Furthermore, they should underscore the importance of promoting a harmonious and positive organizational culture and atmosphere. Naturally, hotel managers must also establish effective communication with employees, assisting them in fostering a desire for excellence in their work.Originality/valueThis study provides valuable insights for the hospitality industry by investigating how illegitimate tasks hold sway over hotel employees’ adaptive performance. The study uses a moderated dual-path model to uncover the mechanisms behind this impact and the influence of boundary conditions, thereby expanding the understanding of the topic.