Mental toughness has been associated with factors related to psychological well-being, but little is known about its relationship with stigma toward mental health and mental health help-seeking. This study investigated the relationship between mental toughness, sport-related well-being, and personal stigma toward mental health in a sample of 154 National Collegiate Athletic Association Division I student-athletes. The moderating effect of mental toughness on the relationship between public stigma and self-stigma toward mental health help-seeking was also explored. Mental toughness was significantly and positively associated with sport-related well-being, but not significantly related to personal stigma toward mental health. Moderation analysis indicated that mental toughness was not a significant moderator of the relationship between public stigma and self-stigma, but higher levels of mental toughness were significantly associated with lower levels of stigma toward mental health help-seeking. Building mental toughness may be a way to increase well-being and to reduce stigma toward help-seeking in student-athletes.