Workplace incivility is a subtle yet harmful form of deviant behavior marked by ambiguous intent to offend, which has become a significant organizational challenge that threatens psychological safety and healthy functioning in an organization. Although past research has examined the experiences of victims and perpetrators of incivility, the point of view of bystanders remain underexplored. The mixed-methods investigation aims to clarify how exposure to workplace incivility shapes bystander behavior in Malaysian workplaces, while testing whether conflict management acts as a mediator and social intelligence serves as a moderator. This study is grounded in the Conservation of Resources Theory and the Bystander Intervention Model. The first phase will involve a large-scale survey of roughly 500 employees across diverse sectors in Malaysia's organizations, which will be conducted using validated measures such as the Workplace Incivility Scale, Rahim Organizational Conflict Inventory-II, Tromsø Social Intelligence Scale, and a Bystander Behaviour Questionnaire. Structural equation modelling will examine the hypothesis. The second phase will involve in-depth, semi-structured interviews with a purposive sample to capture contextual insights and deepen interpretation of the quantitative findings. It is estimated that higher levels of workplace incivility will promote passive or avoidant bystander reactions and reduce constructive intervention, that effective conflict management will explain part of this link, and that strong social intelligence will buffer negative effects by promoting proactive and prosocial responses. By combining the perspectives from organizational behavior, conflict management, and social cognition, this study offers both theoretical contributions and practical guidance to ensure the psychologically safe workplace environments to occur and encouraging active bystander engagement, which will support the Sustainable Development Goals 3 (Good Health and Well-Being) and 8 (Decent Work and Economic Growth).