Surgical traineeship is essential but must be safe for patients. In thyroid surgery, surgeon volume correlates with improved clinical/economic outcomes. However, it is presently unclear how far does trainee participation affect post-thyroidectomy complication rates in real-world and randomized data. We systematically searched four databases for associations of trainee participation with any post-thyroidectomy outcome. We conducted univariate meta-analyses, sensitivity analyses, and assessed publication bias qualitatively and quantitatively. We included 1 randomized and 15 observational studies from 3755 records, comprising 34 774 thyroid surgical patients. Trainee participation was associated with 12 min longer operative time, but not higher complication rates (hypoparathyroidism, recurrent laryngeal nerve palsy, hematoma, blood loss, return to operating room, hospitalization duration, readmission, and mortality). Sensitivity, publication bias, and multivariate analyses did not change our findings. Real-world and limited randomized data suggest that trainee participation in thyroid surgery is safe, given adequate consultant supervision and appropriate case selection.