Background Gender-affirming surgery is a medically necessary treatment to alleviate gender dysphoria for transgender patients. Although previous studies suggest improved psychosocial outcomes after gender-affirming surgery, there are no transgender-specific instruments available to assess its effects on patient quality of life. Methods Using qualitative methods, the authors developed the first quality-of-life survey, the University of California, San Francisco, Gender Quality of Life (UCSF Gender QoL) survey, for trans male patients undergoing gender-affirming mastectomy. The UCSF Gender QoL survey was then administered prospectively to 51 trans male patients undergoing inframammary mastectomy with free nipple grafting at the University of California, San Francisco. The brief version of the World Health Organization Quality of Life survey was also given as a measure of external validity. The Cronbach alpha was value calculated to measure internal validity. Results Thirty-six patients completed surveys 6 weeks after surgery, and 22 patients completed surveys 1 year after surgery, for response rates of 71 percent and 43 percent, respectively. The UCSF Gender QoL survey detected a significant improvement in quality of life 6 weeks and 1 year after chest surgery. The effect sizes were large, and the Cronbach alpha exhibited excellent internal validity. Conclusions This study establishes the UCSF Gender QoL survey as one of the first patient-reported outcomes tools for evaluating quality of life in trans male patients after gender-affirming chest reconstruction. Although the study is limited by a small cohort at a single center, establishing the validity of the UCSF Gender QoL survey provides an invaluable tool for future research into various aspects of gender-affirming chest surgery.