Workplace bullying is considered by the European Agency for Safety and Health at Work one of the emerging psychosocial risk factors that could negatively affect workers’ health. Thus, the aim of this study was to analyze the process that leads from bullying to negative health (such as musculoskeletal disorders (MSDs)), testing the mediating role of job-related strain. Data were collected on 512 workers (62.9% female; mean age = 43.6 years) of a retail chain who filled in a self-report questionnaire after a one-hour training session on work-related stress. Data analyses were performed controlling for potentially confounding variables (i.e., gender, age, organizational role, type of contract, and perceived physical job demands). Preacher and Hayes analytical approach was used to test the indirect relationship between bullying and MSDs. Results showed that work-related strain mediates the relationship between bullying and MSDs considered (low back, upper back, and neck) except for MSDs of the shoulders. Our study confirms the role played by bullying and job-related strain in determining workers’ MSDs.