Introduction: Digital mental health interventions are on the rise; yet people with intellectual disabilities are not generally seen as their potential users. This study aims to explore the accessibility of two mainstream online mood-management programmes. Methods: Using a qualitative study design, 12 adults with intellectual disabilities were interviewed while accessing moodgym and iFightDepression®. Thematic analysis was used to explore the programs' accessibility according to the technology acceptance model. Results: The programs' ease-of-use was considered in terms of visual appeal, support needs, and essential skills for independent program use. Perceived usefulness concerned participants' understanding of the purpose and expected personal benefits associated with the interventions. Finally, intention to use and motivation to interact with the interventions were key aspects of participants' attitudes toward them. Conclusion: Improving intervention accessibility is a first important step to ensure people with intellectual disabilities can understand the purpose and content of digital mental health interventions.