We investigated how and when paradoxical leader behaviour (PLB) positively influenced employee taking charge, a typical exemplar of proactive behaviours. Participants were 644 employees of a large Chinese high-tech manufacturing company (male = 50.8%; mean age = 29.63 years, SD = 5.72 years). Based on hierarchical regression analysis and bootstrap analysis, the results indicated that PLB was associated with a higher probability of employee taking charge, with role breadth self-efficacy (RBSE) acting as a mediator for this relationship. Furthermore, promotion focus moderated this mediation relationship, such that the relationship was stronger for subordinates high in promotion focus. We concluded that contextual factor of PLB and individual differences of promotion focus were essential to enhance employees' perception of RBSE and possibilities of taking charge.