While exposure therapy is the most effective psychological treatment for obsessive-compulsive, anxiety, and traumatic stress-related disorders, it is not universally effective, indicating a need for further treatment optimization. This study investigated a shift in approach to exposure therapy with 29 treatment-refractory adults in an OCD clinic not responding to standard treatment, comprising habituation-based exposure therapy. Participants completed a standard exposure as continuation of standard clinic treatment, followed by an Acceptance and Commitment Therapy (ACT) consultation session to assess psychological inflexibility processes interfering with treatment progress, and then an ACT-based exposure targeting behavior change through increasing psychological flexibility. After each exposure, participants and independent raters reported levels of psychological flexibility, rituals, distress, treatment engagement, and treatment perceptions. We observed that the shift to ACT-based exposure was associated with greater psychological flexibility, treatment engagement, treatment acceptability, and treatment preference. These findings suggest there may be situations where ACT-based exposure has particular utility.