This study explores the academic, professional, and personal career benefits of leading science, technology, engineering, and mathematics (STEM) outreach, from the perspective of undergraduate student leaders. We consider traditional and nontraditional STEM university students, gender, and type of position (paid or volunteer) in this evaluation. Data were collected through an online survey completed by 30 former student STEM outreach leaders from the University of British Columbia. Self-reported survey data indicated that STEM outreach had a moderately strong average impact of 6.89 ± 1.55 out of 10 on participants' personal, academic, and professional development, with no significant differences between these areas. Outcomes did not differ between genders, and paid work was found to contribute to greater personal and professional impact. The positive influence of outreach on academic and professional decision making was higher in traditional STEM fields than STEM-based health-science studies. The outcomes of this research adds insight into positive impacts of STEM outreach on university student instructors.