Obsessive-compulsive disorder commonly co-occurs with autism. Research characterising the interplay between restricted, repetitive behaviours, activities and interests related to autism and obsessive-compulsive disorder symptoms has used theory-driven, bottom-up methodology. This study aimed to interview autistic adults about the subjective experience of differentiating between these phenomena. Semi-structured interviews were conducted with 15 autistic adults experiencing obsessive-compulsive disorder symptoms and repetitive behaviours, activities and interest. Transcripts were analysed using reflexive thematic analysis from a critical-realist, inductive orientation. Three overarching themes are presented. Participants viewed repetitive behaviours, activities and interest as intrinsic to their identity, while obsessive-compulsive disorder remained ego-dystonic and a perpetuator of anxiety. Conversely, repetitive behaviours, activities and interest was present across various emotions, often serving as a method to manage anxiety. Routinised behaviours and focused interests were considered by participants to be vulnerable to obsessive-compulsive disorder exploitation. Although participants reported masking both phenomena, the methods and motivations to mask differed. This research demonstrates the importance of delineating these experiences, with suggestions offered in how to explore this with autistic clients. Future research could explore narratives of masking obsessive-compulsive disorder across autistic and non-autistic people and investigate simultaneous co-occurrence of obsessive-compulsive disorder and repetitive behaviours, activities and interest; including how focused interests may influence obsessive-compulsive disorder and how repetitive routines may be intensified by obsessive-compulsive disorder.