The efficacy of psychedelic-assisted therapies for mental disorders has been attributed to the lasting change from experiential avoidance to acceptance that these treatments appear to facilitate [1]. However, it is still insufficiently understood how exactly this change occurs. Here we build on the recently proposed relaxed-beliefs account of the acute brain action of psychedelics [2] to present a conceptual model that specifies the psychological mechanisms underlying the acceptance-promoting effects of psychedelic therapy [3]. Our model shows substantial parallels between psychedelic therapy and cognitive behavioral therapy (CBT): We propose that in the carefully controlled context of psychedelic therapy as applied in contemporary clinical research, psychedelic-induced belief relaxation can increase motivation for acceptance via operant conditioning, thus engendering episodes of relatively avoidance-free exposure to greatly intensified private events (emotions, body sensations, memories etc.). Under these unique learning conditions, relaxed avoidance-related beliefs can be exposed to corrective information and become revised accordingly, which may explain long-term increases in acceptance and corresponding reductions in psychopathology. Open research questions and implications for clinical practice are discussed. Although still requiring further empirical support, the proposed model demonstrates the usefulness of the relaxed-beliefs account as a basis for building theories of the therapeutic effects of psychedelic drugs.