There is evidence that rehabilitation with a multidisciplinary focus on work-related demands effectively improves work ability and quickens return to work in patients with musculoskeletal disorders. There could be benefits to the transfer of work-related components into rehabilitation aftercare. We examined the effectiveness of an intensified work-related rehabilitation aftercare program compared with standard intensified rehabilitation aftercare in Germany on work ability. We randomly assigned 307 patients with musculoskeletal disorders from 11 rehabilitation centers to an aftercare program with work-related functional capacity training, work-related psychosocial groups, social counseling, relaxation training and exercise therapy (intervention group), or the usual aftercare program consisting of only exercise therapy (control group). The 6-month follow-up questionnaire was completed by 78.5% of patients. There was no statistically relevant between-group difference in follow-up primary (work ability) and secondary outcomes (e.g. health-related quality of life, sick leave duration). Significant improvements were observed within both the intervention and the control groups. Severely disabled participants in the intervention group had better physical functioning and shorter sick leave duration after 6 months compared with severely disabled patients in the control group. A partial replacement of standard exercise therapy by a more work-related therapy does not seem to improve work ability superiorly. Improved aftercare treatment may require a focus on employer participation and involvement within the actual work environment.