ABSTRACT Introduction The impact of instant messaging (IM) tools on employee workload is a concern in both academic and professional contexts. Despite the widespread use of mobile instant messaging (MIM) and its challenges for organizations, research on this topic remains limited. Objective This study aims to explore the mediating roles of interactivity and job interruption, and the moderating role of communication quality, in the relationship between MIM use and perceived workload, using the job demands-resources model, distraction-conflict theory, and media synchronicity theory. Method A total of 235 employees completed self-report questionnaires measuring MIM use, interactivity, job interruption, perceived workload, and communication quality. Results The study found that MIM use has indirect effects on perceived workload. While MIM usage increases interactivity, reducing perceived workload, it also increases job interruptions, leading to a higher perceived workload. Mediation analysis showed that both job interruption and interactivity mediate the MIM use-workload relationship. Furthermore, communication quality weakens the negative impact of interactivity on perceived workload and the positive impact of job interruption on perceived workload. Conclusion These findings challenge the belief that IM is solely disruptive in the workplace, highlighting the importance of communication quality for effective management. This enhances our understanding of MIM's role in corporate and personal productivity.