Purpose Although common mental disorders (CMDs) highly impact individuals and society, a knowledge gap exists on how sickness absence can be prevented in workers with CMDs. This study explores: (1) workers’ perceived causes of sickness absence; (2) perceived return to work (RTW) barriers and facilitators; and (3) differences between workers with short, medium and long-term sickness absence. Methods A longitudinal qualitative study was conducted involving 34 workers with CMDs. Semi-structured interviews were held at two time-points during their RTW process. The 68 interviews were audio-taped, transcribed and thematically analyzed to explore workers’ perspective on sickness absence causes, RTW barriers and facilitators, and compare data across the three sub-groups of workers. Results Workers reported various causes for their absence, including: (1) high work pressure; (2) poor work relationships; (3) unhelpful thoughts and feelings, e.g. lacking self-insight; and (4) ineffective coping behaviors. According to workers, RTW was facilitated by work adjustments, fulfilling relationships with supervisors, and adequate occupational health guidance. Workers with short-term leave more often reported favorable work conditions, and proactive coping behavior. In contrast, the long-term group reported reactive coping behavior and dissatisfaction with their work. Conclusion Supporting workers with CMDs in gaining self-awareness and regaining control, discussing the value of their work, and creating work conditions that enable workers to do valuable work, seem central for successful RTW and might prevent sickness absence. Supervisors play a key role in enabling workers to do valuable work and further research should focus on how supervisors can be supported in this task.