PURPOSE: Often, body mass index (BMI) thresholds may be used to determine surgical candidacy in gender-affirming chest masculinization, but evidence for using these as surgical criteria has not been established. We sought to analyze a national cohort of patients undergoing mastectomy for gender affirmation to assess the risk of postoperative complications among different BMI categories. METHODS: The National Surgical Quality Improvement Program database (from 2010 to 2020) was queried to identify all encounters of mastectomy for gender affirmation. Cases were stratified by BMI categories and 30-day postoperative medical and surgical complications were compared. RESULTS: A total of 10,775 patients were queried. The overall proportions of medical complications remained low for all groups. Incremental increases in the proportions of readmission, return to the operating room, wound infection, and wound dehiscence were observed with each increase in BMI category (=0.001). A multivariate regression model controlling for age, diabetes, American Society of Anesthesiologists (ASA) class, and operative time demonstrated a statistically significant increase in odds ratio (OR) for complications in the obesity II (OR 1.59, <0.001) and obesity III (OR 1.85, <0.001) cohorts. Age (OR 1.08, <0.001), diabetes (OR 1.4, =0.016), and increased operative time (OR 1.22, <0.001) were independently associated with an increase in odds of surgical complications. CONCLUSIONS: While the obesity II and III cohorts experienced increased odds of complications, the authors suggest that these complications are not prohibitive. In the setting of comprehensive informed consent, obesity alone should not act as a contraindication to surgery in suitable candidates.