This single case study illustrates the application and utility of Acceptance and Commitment Therapy (ACT) for a 72-year-old Australian male presenting with chronic pain and complex health conditions. Chronic pain often entails complexity among older adults and can impact the patient’s life across a range of domains. Psychological approaches, as stand-alone or adjunct to medical intervention, are widely acknowledged as potentially beneficial to older persons experiencing pain. ACT has been supported as a viable psychological approach for chronic pain and especially suitable for older persons with chronic pain. This study describes an ACT treatment approach for an older person with chronic pain informed via development of an extension of the existing ACT conceptualization of chronic pain. The development of the ACT based model is in keeping with recommendations to seek out mechanisms of change in psychotherapeutic research. Measures of Quality of Life, Depression, Physical Activity, and Acceptance/Avoidance were taken at pre and post treatment, as well as across treatment phases. Improvement was noted in self-reported measures of QOL, depression, and physical activity.