This study is aimed at identifying the impact of a team-based train-the-trainer program (TTT-P) to enhance healthcare professional (HCP) skills in patient education during medical rehabilitation. Focusing on patient-reported outcomes, a prospective, sequential two-cohort study was conducted in the fields of psychosomatic and oncological rehabilitation. Two hundred fifteen patients were evaluated before (Cohort 1) and 196 post implementation of TTT-P (Cohort 2). Patients of both cohorts completed validated questionnaires on self-management (heiQ[R]), general self-efficacy (GSE scale), and quality of life (WHOQOL-Bref) at the beginning, at the end, and at the 6-month follow-up to analyze short- and intermediate-term effects. Analyses were conducted separately for the psychosomatic and oncological setting. Results showed that TTT-P had no impact on patient outcomes in both rehabilitation settings. Patients did report positive outcomes as a result of the whole inpatient rehabilitation programs, though effects at follow-up were mostly small to medium size. Concerning self-management competencies, cancer patients gained less benefit during rehabilitation than psychosomatic patients. In conclusion, TTT-P did not result in measurable improvements at the patient level, likely because of the limited nature of the intervention. However, these populations of rehabilitants took benefit from participating in a multimodal rehabilitation program, of which patient education is one part.