Limited evidence supports treatment for distress in life-threatening illness. Psychedelic-assisted psychotherapy (PAP) may help. Despite music's presence in PAP, sparse accounts of music-related experiences exist. Such research is needed to optimize music's presence within PAP. This qualitative analysis aimed to understand participants' music-related accounts of their PAP experiences within a randomized controlled trial (RCT) for depression and anxiety associated with life-threatening illness, and participants' perceived mechanisms of change attributed to music during PAP. Participants undergoing an 11-session, manualized PAP RCT (with open-label extension) engaged in semi-structured interviews post-dose one (psilocybin or control ingestion) and post-dose two (psilocybin). Interviews examined participants' PAP experiences. A music therapist-led thematic analysis informed by grounded theory was conducted on music-related interview content. Thirty-one participants gave at least one post-dose interview. Four themes were generated: music during psilocybin ingestion can connect, interplay, and integrate with deep multisensorial, somatic, and mental realms; awareness of these far-reaching realms (one's essence) can be catalyzed by music and PAP; awareness of this essence can be revelatory, fragmenting, or both; and music can access PAP legacy sensations, spawning ongoing processing. Participants felt more intensely connected to music in psilocybin compared to control sessions. A data display illustrates participants' perceived mechanisms of change attributed to music during PAP preparation, dosing, and integration. Findings were compared with a psychiatrist-led phenomenologically framed analysis of the same data set. Both analyses extend conceptualizations about music in PAP and managing discordant inter-rating in qualitative research. Implications for music therapy and PAP, informed by the authors' collaboration, are considered.