© 2022Introduction: Pain after a mastectomy is one of the most common problems experienced by women with breast cancer. This study aimed to identify the effects of foot massage on upper extremity pain and quality of life in women with breast cancer who underwent a mastectomy. Methods: This study employed a mixed-method design. The quantitative phase was conducted as a randomized controlled trial in which the intervention group received a series of foot massages and the control group received standard care. The qualitative phase consisted of semi-structured interviews conducted before the first follow-up with the participants in the intervention and control groups and at the end of the sixth follow-up with the intervention group. Results: In comparison to the participants in the control group, the participants in the intervention group were found to have significantly lower mean VAS pain scores at the first, fourth, fifth, and sixth follow-ups. In addition, a significant difference was found between the intervention and control groups before and after the intervention regarding their quality of life. Conclusion: The results of this study indicated that foot massage was effective in reducing pain, but less effective in improving the quality of life, in women with breast cancer who underwent a mastectomy.