Methadone maintenance therapy (MMT) is a harm reduction-based approach that has been part of national policies since 2018. Despite its inception, MMT provision faces challenges, particularly in North Thailand, where opioid use disorders are the most prevalent. This study assessed MMT provisions in terms of system input, performance, and output in all 147 public hospitals under the Ministry of Public Health in Northern Thailand. This cross-sectional study employed an online questionnaire based on the World Health Organization’s six building blocks and the Non-adoption, Abandonment, Scale-up, Spread, and Sustainability (NASSS) framework. Northern Thailand data collection spanned from September 1, 2022, to February 1, 2023. The results revealed that ninety-eight hospitals (66.70%) responded. Only 37.76% actively provided MMT, 4.08% discontinued it, and 58.16% did not offer it. In areas where opioid overuse disorder is reported, MMT is available in 70.59% of the hospitals. The strong system governance and value proposition of MMT in hospitals with MMT services helped 78.49% of patients with opioid use disorder access services and maintained a one-year retention rate of 71.35%. Though patients with MMT services had a high retention rate, gaps still existed such as a lack of staff and training, limited data collection, and insufficient collaboration with stakeholders to expand the referral capacity. Inactive and pending hospitals lacked an MMT service policy, hindering service launches. According to the findings, the scaling up of MMT services still faces challenges, including the fact that most hospitals do not offer these services and even those that do often lack staff, training, and resources. Support for MMT services must be tailored to the specific needs and contexts of different hospitals.