Objective Few empirical studies have explored cancer‐related experiences of people with an intellectual disability (ID), despite rising cancer incidence in this population. The present research aims to better understand the experiences of this population from multiple perspectives, generating theory and further research questions. Methods Six people with ID and cancer, alongside 12 participants from their supportive network (including family and social and health care professionals), were interviewed; transcripts were analyzed using grounded theory. Results People with ID were often overlooked within cancer consultations and excluded from conversations about their care and treatment‐related decisions. Caregivers (family and paid) were relied upon to facilitate communication and understanding and supplement health care professional knowledge. Caregivers' attempts to protect the patient from distress harmed communication further; our interviewees suggest that increased involvement and empowerment mediated cancer‐related distress. Where health care professionals possessed good patient‐centered skills, and additional support was offered, people with ID were more likely to engage meaningfully in their cancer‐related experience. Conclusions Interestingly, emergent concepts were consistent with general psycho‐oncology literature; however, incidence and severity of difficulty was substantially greater in this sample. This disparity warrants further exploration, with a need for intervention research to develop effective ways of supporting health care professionals in enhancing patient‐centered skills with this population. In the clinical setting, patient involvement in health care decisions (despite problems associated with comorbidity) is imperative to optimize engagement.