Background: Limited evidence exists on patient-relevant outcomes after high tibial osteotomy (HTO), including return to work (RTW). Furthermore, prognostic factors for RTW have never been described. Purpose: To investigate the extent and timing of RTW in the largest HTO cohort investigated for RTW to date and to identify prognostic factors for RTW after HTO. Study Design: Cohort study; Level of evidence, 3. Methods: Consecutive patients who underwent HTO between 2012 and 2015 were included. Patients received a questionnaire at a mean follow-up of 3.6 years. Questions were asked pre- and postoperatively regarding work status, job title, working hours, preoperative sick leave, employment status, and whether patients were their family’s breadwinner. The validated Work Rehabilitation Questionnaire (WORQ) was used to assess difficulty with knee-demanding activities. Prognostic factors for RTW were analyzed using a logistic regression model. Covariates were selected based on univariate analysis and a directed acyclic graph. Results: We identified 402 consecutive patients who underwent HTO, of whom 349 were included. Preoperatively, 299 patients worked, of whom 284 (95%) achieved RTW and 255 (90%) returned within 6 months. Patients reported significant postoperative improvements in performing knee-demanding activities. Being the family’s breadwinner was the strongest predictor of RTW (odds ratio [OR], 2.92; 95% confidence interval [CI], 1.27-6.69). In contrast, preoperative sick leave was associated with lower odds of RTW (OR, 0.20; 95% CI, 0.08-0.46). Conclusion: After HTO, 95% of patients were able to RTW, of whom 9 of 10 returned within 6 months. Breadwinners were more likely to RTW, and patients with preoperative sick leave were less likely to RTW within 6 months. These findings may be used to improve preoperative counseling and expectation management and thereby enhance work-related outcomes after HTO.