Purpose With the emergence of a variety of communication channels on social media, employees have more opportunities to engage with external stakeholders for or against their organizational brand. In such a context, focusing on negative word-of-mouth (NWOM) as an employee’s negative discretionary brand-oriented behavior, the current study aimed to identify negative emotions that can serve as drivers for NWOM more strongly than for counterproductive workplace behavior (CWB), relying on the discrete emotion perspective. This study also aimed to examine whether employees’ perceived brand knowledge can directly diminish employees’ NWOM and CWB and attenuate the influence of negative emotions. Design/methodology/approach A questionnaire was used to gather relevant data, which were analyzed by structural equation modeling. Findings The findings showed that anger was more strongly associated with employees’ NWOM than withdrawal and that envy was more strongly associated with CWB toward individuals than employees’ NWOM. Employees’ perceived brand knowledge was negatively associated with both NWOM and CWB directly and mitigated the association of negative emotions such as anger and envy with CWB, but not with NWOM. Originality/value Based on the discrete emotion perspective, the current study explored the relative magnitude of emotional antecedents for employees’ NWOM and conventional CWB. Also, it expanded the previous findings on the positive effects of perceived brand knowledge on the positive outcomes of employees’ actions and its mitigating effects on NWOM and CWB.