Background: First responders (firefighters, paramedics, and police officers) typically involve repeated, often chronic, exposures to potentially psychologically traumatic events. When combined with insufficient social support and reduced help-seeking behaviours, such exposures may increase the risk of mental health challenges, particularly among paramedics who report the highest rates of mental disorders. Objective: The current study used the Theoretical Domains Framework (TDF) and the Consolidated Framework for Implementation Research (CFIR) to identify critical barriers and facilitators to help-seeking and accessing mental health care, and the feasibility and long-term sustainability of a First Responder Operational Stress Injury Clinic in Ottawa Canada. Methods: Semi-structured qualitative interviews included 11 paramedics (frontline, mid-and-senior management, and union), recruited using purposive and snowball sampling. Interviews were analyzed using content and thematic analyses. The TDF and CFIR guided study design, interview content, data collection and analysis, and the interpretation and reporting of results. Results: The findings underscore the pervasive and troubling nature of several barriers, including the complexities of stigma, confidentiality, cultural competency and humility, and trust. The results also highlight the influence of environmental context and availability of resources on help-seeking and accessing mental health care. Data saturation was reached when there were no new barriers or facilitators produced on help-seeking and accessing mental health care. Conclusion: The findings on cultural competency and humility are an important contribution to the literature given the scant research within first responder mental health. Further, this research will be instrumental in informing evidence-based approaches to mental health care for paramedics, particularly during and after COVID-19. This study can also serve as a helpful approach to replicate in order to determine how best to provide mental health services specific to other populations.