Most autistic adolescents experience anxiety. Interoception, defined as one's ability to detect and interpret bodily signals, might contribute to this. The aim of this exploratory, qualitative study was to gain a better understanding of interoceptive experiences in autistic adolescents and how this relates to anxiety. Semi-structured 1:1 interviews were conducted with 13 UK-based, autistic adolescents, aged 14-17 years, who reported experiencing significant, day-to-day anxiety. Interviews were analysed using a reflexive thematic analysis approach. Interoception appeared relevant to experiences of anxiety in most participants, although this influence was exerted through various routes. While hypoawareness of interoceptive signals led to a reduced ability to detect and regulate anxiety, hyperawareness became overwhelming and anxiety-inducing. Overly negative evaluations of interoceptive signals, including catastrophising about the signals indicating danger, also triggered anxiety. Relationships between interoception and anxiety appeared bidirectional, with anxiety also affecting interoceptive awareness and evaluation. Interoceptive experiences were variable both across and within participants, with factors such as arousal and cognitive overload affecting experiences. Future research should focus on assessing the feasibility of interventions based on the mechanisms identified here.