Background Multidrug-resistant tuberculosis (MDR-TB) remains a public health crisis and a health security threat worldwide. Poor public health infrastructure, inefficient infection control and mismanagement of TB treatment are among the reasons for the continuous emergence and spread of drug-resistant TB (DR-TB). The final treatment outcome is the most direct measurement of TB control programs. Therefore, this study sought to determine the proportions and predictors of TB treatment outcomes among MDR/RR-TB treated patients. Methods A 10-year, 2011 to 2021, hospital-based retrospective cohort study was conducted at the University of Gondar Comprehensive Specialized Hospital. The records of 408 MDR-TB patients, 389 with treatment outcome and 19 on treatment, were collected using a structured checklist. Results A total of 389 patients with a recorded MDR/RR-TB treatment outcome were included. The treatment success rate was 77.12%, with 58.35% cured and 18.76% treatment completed. The proportion of death rate, treatment default loss to follow-up, treatment failure, and unknown treatment outcome was 9.25%, 6.94%, 3.1%, and 3.6%, respectively. Regarding the patient category, the most successful treatment outcome (83.5%) came from patients diagnosed with relapse cases, followed by new cases (81.8%). An unsuccessful treatment outcome was significantly associated with patients aged >44 years (AOR, 3.3, 95% CI = 1.55–6.99). Conclusion and Recommendations This study indicated that nearly 23% of MDR/RR-TB patients had unsuccessful treatment outcomes and being older was significantly correlated with these outcomes. For better outcomes, it is recommended to strengthen combined treatment adherence interventions and evaluate treatment regimens and administration options. A prospective cohort study may be required to investigate the full range of potential causes of unfavorable outcomes.