OBJECTIVES: Chronic pain is often associated with lower function. Self-criticism is associated with depressive symptoms. The purpose of this study was to explore if fusing Acceptance and Commitment Therapy and compassion-focused therapy could improve psychological well-being and disability in individuals with chronic pain with high levels of self-criticism in comparison to a wait-list control group. METHODS: Individuals with chronic pain (n=71) were randomly assigned to an 8-week internet-based intervention focused on acceptance and compassion or a wait-list condition. Primary treatment outcomes were the Chronic Pain Acceptance Questionnaire, Self-Compassion Scale, and Pain Disability Index. Secondary outcomes were the Montgomery Åsberg Depression Rating Scale, Anxiety Sensitivity Index, Quality of Life Inventory, Multidimensional Pain Inventory, and Perseverative Thinking Questionnaire. RESULTS: Missing data at postintervention were 22.5%. Intention-to-treat analyses were conducted using linear mixed models. The results revealed greater levels of acceptance and self-compassion for the treatment group, which were primary outcomes, with effect sizes ranging from small to large, and these results were maintained at 6-month follow-up. The rates of clinically significant improvements were also greater for the treatment group in comparison to the wait-list control group on acceptance and compassion. The treatment group also improved in the third primary outcome, pain disability. Significant differences were found in several of the secondary outcomes, in favor of the treatment group. DISCUSSION: Internet-based Acceptance and Commitment Therapy with compassion-focused therapy components shows promise as a viable treatment option in the management of chronic pain.