Autistic people are more likely to experience physical and mental health difficulties across the lifespan, leading to an increased risk of premature mortality likely due to health disparities. At present, little is known about the healthcare experiences of autistic older adults. Semi-structured interviews were conducted with 19 autistic adults aged 65 years or over living in the United Kingdom. Reflexive thematic analysis produced these themes: (1) A lifetime of being misunderstood; (2) Autistic people falling between the gaps; (3) Processing autism diagnosis in later life; (4) Concerns about service pressures and scarce resources; (5) Lack of continuity of care, empathy and understanding; (6) Anxiety, alexithymia and sensory overload; and (7) Reduced social support and concerns for the future. Some of the challenges autistic older adults faced were like those experienced by younger or middle-aged autistic adults. However, they also reported additional difficulties related to ageing and lifelong experiences of social exclusion. These difficulties were made worse by increased service pressures. A comprehensive approach is needed, including enhanced staff training, personalised care, targeted support and policy changes. Services should also consult with autistic older adults so they can advocate for their care, shape policy and co-design services.