Chronic pain is a common, multifactorial problem that requires medical and psychological interventions to be managed. On the other hand, Acceptance and commitment therapy (ACT) is one of the third-wave cognitive-behavioral therapies, which has recently been used to treat the certain psychiatric disorders and to enhance the patients’ psychological status. Therefore, the present study aimed to investigate the effectiveness of acceptance and commitment therapy on reducing pain intensity and improving the sense of coherence and psychological well-being among the patients with chronic low back pain. This quasi-experimental study was performed by a pretest-posttest design with two groups. Also, it had a statistical population including all the patients with chronic low back pain and were present at the neuropsychiatry clinic of Ali ibn Abi Talib Hospital, who were referred to Red Crescent Physiotherapy Clinic in Zahedan from March 2016 to May 2017. Moreover, its sample consisted of 30 patients with chronic low back pain who were selected from all the patients referred to Red Crescent Physiotherapy Clinic in Zahedan, using the targeted sampling method in terms of the inclusion and exclusion criteria. These patients were then assigned into two groups as experimental and control, each one included 15 patients. In addition, the McGill Pain Questionnaire (1997), The Ryff Psychological Well-being Scale (1989), and the Sense of Coherence Scale designed by Flensborg-Madson et al. (2006) were used as data collection tools. To analyze the data, descriptive statistics such as means, standard deviations, and univariate and multivariate covariance analyses were used. The data analysis indicated that, the acceptance and commitment therapy could significantly decrease the pain intensity and its subscales among the patients in the experimental group compared to the control group (P<.01). Furthermore, acceptance and commitment therapy significantly increased the sense of coherence and psychological well-being as well as their subscales in the experimental group's patients compared to the control group (P<.01). It can be concluded that, acceptance and commitment therapy was effective on reducing the pain intensity and boosting the sense of coherence and psychological well-being among the patients with chronic low back pain. Therefore, the findings represent new horizons in clinical interventions and can be used as an effective intervention method.