Regulation of the mental health and substance use health (MHSUH) workforce affects not only quality but also the availability and accessibility of services. This study explores the perspectives of subject matter experts on how flexible, modern regulatory reforms in the MHSUH workforce can promote more equitable access to services and the impact of regulation on service safety, quality, accessibility, and the workforce. Between January and March 2023, semi-structured interviews were conducted with 15 subject matter experts from diverse MHSUH provider groups and organizations. Participants shared insights on regulation, quality assurance, and relevant policies that shape equitable access to MHSUH services and workforce dynamics. The data were analyzed thematically, and findings were validated by the project’s diverse advisory committee. The analysis generated four themes that underscore the need to re-imagine regulatory approaches in a way that makes room for the dynamic tension between standardization and protection of the public on the one hand, and flexibility and respect for the value of lived expertise on the other. These themes include: (1) the impact of policy exclusion, criminalization, and stigma of MHSUH; (2) gaps in regulation limit access and the protection of the public; (3) the dynamic tension between standardization and flexibility in regulatory approaches; and (4) policies to support the integration of lived experience into the MHSUH and broader health workforce are limited. In conclusion, re-imagined regulatory approaches are essential for ensuring equitable access to MHSUH services and addressing significant gaps in workforce planning. An adapted right-touch regulation approach, which aligns regulatory interventions with the level of risk, may help guide future reforms for the MHSUH workforce in Canada. This approach should balance the need to appropriately manage risks of harm while avoiding unnecessary barriers to practice across the spectrum of MHSUH providers.