Background: Although the World Health Organization designates opioids as an essential medication and recommends them as the cornerstone for managing moderate to severe cancer pain, their accessibility is severely restricted, particularly in low and middle-income countries. Despite Vietnam's early endeavors in the advancement of palliative care, including a revised opioid prescription policy in 2008, opioid use for cancer pain remains suboptimal, with oral morphine available only in a few major hospitals. To inform comprehensive strategies for improving opioid access, this study aims to explore the views of healthcare providers, regulators, cancer patients, and caregivers in Vietnam on the barriers to safely accessing opioids for cancer pain management. Methods: We conducted a qualitative, descriptive study and recruited five healthcare providers, six cancer patients and caregivers, and six regulators (i.e., policymakers in the Ministry of Health, heads or deputy heads of pharmacy, oncology, or palliative care departments) across Vietnam via purposeful sampling technique. Data were collected using semi-structured interviews, and the audio recordings were transcribed verbatim and subjected to inductive content analysis using a Framework Method. Results: Five categories of barriers were identified: 1) Patient-related barriers (fear of addiction and other side effects, morphine's association with impending death, negative administration experiences, religious beliefs); 2) Professional-related barriers (knowledge and experience deficit, fear of addiction and other side effects, concerns about opioid diversion and associated liabilities, lack of guidance, education, and training); 3) Medicine-related barriers (limited oral morphine availability, limited domestic pharmaceutical manufacturers and suppliers, supply interruptions, poor variety of opioid types and formulations, difficulties accessing parenteral opioids); 4) Services delivery barriers (scarce palliative and home care services); 5) Regulatory barriers (lack of information on opioid distribution channels, difficulties obtaining confirmation letters for patients' opioid usage needs, overly strict regulation enforcement). Conclusions: Barriers to opioid access for cancer pain control in Vietnam are multifactorial and mutually reinforcing, necessitating interdisciplinary solutions to overcome them. This approach should involve enhancing education about the appropriate use and management of opioids, along with current opioid policies for patients, communities, healthcare providers, and regulators; enacting and implementing policies mandating oral morphine availability at local health facilities; expanding palliative care services; utilizing telemedicine; and establishing an electronic opioid prescription monitoring system.