Purpose: The present study aimed to determine the effectiveness of Acceptance and Commitment Therapy (ACT) on physical activity, body appreciation, and body image flexibility in women experiencing premenstrual syndrome (PMS) symptoms.

Materials and Methods: This study was quasi-experimental with a pretest–posttest–follow-up control group design. The statistical population comprised all women referring to healthcare centers in Tehran. From this population, 30 women were selected using purposive sampling and were randomly assigned to either the experimental or control group. For the pretest, posttest, and follow-up assessments, participants completed the Premenstrual Syndrome Assessment Scale, the Health-Promoting Lifestyle Profile (HPLP), the Body Appreciation Scale (BAS), and the Body Image–Psychological Inflexibility Scale (BIPIS). The experimental group received Acceptance and Commitment Therapy over 10 ninety-minute sessions. Data were analyzed using repeated-measures ANOVA via SPSS-27.

Findings: The findings indicated that Acceptance and Commitment Therapy had a significant effect on premenstrual syndrome symptoms, physical activity, body appreciation, and body image flexibility, and these therapeutic effects remained stable over time (P < 0.05).

Conclusion: These findings suggest that Acceptance and Commitment Therapy can be utilized as an effective psychological intervention in healthcare settings to alleviate premenstrual syndrome symptoms and promote adaptive lifestyle behaviors, body appreciation, and psychological flexibility among women.