Access to essential health services is a basic human right, yet many cancer patients living in conflict-affected regions face multiple obstacles to service use. The (former) Nagorno-Karabakh Republic was a conflict-affected region in the South Caucasus populated predominantly by ethnic Armenians. Multiple acute armed conflicts, the recent military occupation of the region, and the prolonged military blockade of the Lachin Corridor (a humanitarian corridor connecting Nagorno-Karabakh to Armenia) exacerbated existing social, health, economic, and political fragilities in this region. As a result, cancer services were disrupted, with limited clarity on how the ongoing military blockade of a humanitarian corridor affected cancer patients' experiences of accessing cancer care locally and in bordering Armenia. Our study aimed to describe the experiences of patients from Nagorno-Karabakh in accessing the cancer care services they needed. We conducted remote semi-structured interviews with adult (aged ≥18 years) cancer patients receiving cancer care from three university hospitals in Armenia and face-to-face interviews with cancer care professionals from these hospitals. Interviews were conducted during the blockade of the Lachin Corridor between March and May 2023. Data were analysed thematically using a deductive approach. Twelve adult cancer patients (9 women) and 12 cancer care professionals participated. A key barrier to accessing cancer services was attributed to the Azerbaijani military occupation of the region and the blockade of a major roadway connecting Nagorno-Karabakh to Armenia. Patients talked in length about the challenges of finding transport and travelling long distances to reach essential cancer services in Armenia. Policies of free anti-cancer medication provision and decentralised medication supply were paused because of the military occupation, affecting patients' timely access to anti-cancer medication. Out-of-pocket expenses for treatment, anti-cancer medication, travel, and temporary accommodation in Armenia placed a significant financial burden on cancer patients, exacerbated by the humanitarian crisis. Conflict-affected regions blockaded by military forces lack the capacity and targeted support to sustain their essential health services and provide care to those in need of life-saving treatments. Coordinated action from national and international organisations and governments is urgently needed to enhance humanitarian assistance and healthcare support to patients, their families and wider communities affected by military blockades and armed conflicts.