Tynes is from Detroit. Her mother worked for Chrysler. She completed her bachelor's degree in history at Columbia University, then moved to Northwestern University for her graduate studies, where she specialised in learning sciences. Tynes was a graduate student at University of California, Los Angeles, studying the relationship between youth identity and the internet. She was a researcher in the laboratory of Patricia Greenfield, who was investigating the construction of sexual identity online. Tynes has said that her research was inspired by the Kenneth and Mamie Clark. After graduating, Tynes worked as a high school global studies teacher.

Tynes studies youth engagement with social media, and how this impacts their academic outcomes. She was the first to identify that adolescents of color were most likely to suffer from online victimization. This victimization can result in increased depressive tendencies and decreased academic motivation. Working with the National Institutes of Health, Tynes studied race-related cyberbullying. Through the development of a risk and resilience framework, Tynes has shown that whilst online interactions can threaten the social identify of adolescents, there are strategies to mitigate this.Based on her research, Tynes developed a mobile-driven application that helps young people cope with online racial discrimination. The application was evaluated using a randomized control trial. Tynes was the founder of the Digital Equity Project, an investigation into the use of mobile devices in K–12 schools. She showed that the regular exposure to traumatic incidents that involved people of color online can result in poor mental health outcomes.Tyne joined the University of Michigan as a Visiting Associate Professor in 2015.

2010 Diverse Magazine Emerging Scholars under 40 2012 AERA Early Career Contribution Award 2015 Spencer Foundation Midcareer Award 2015 American Educational Research Association Early Career Award

Subrahmanyam, Kaveri; Greenfield, Patricia M.; Tynes, Brendesha (2004-11-01). "Constructing sexuality and identity in an online teen chat room". Journal of Applied Developmental Psychology. Developing Children, Developing Media - Research from Television to the Internet from the Children's Digital Media Center: A Special Issue Dedicated to the Memory of Rodney R. Cocking. 25 (6): 651–666. doi:10.1016/j.appdev.2004.09.007. ISSN 0193-3973. Tynes, Brendesha M. (2007-11-01). "Internet Safety Gone Wild?: Sacrificing the Educational and Psychosocial Benefits of Online Social Environments". Journal of Adolescent Research. 22 (6): 575–584. doi:10.1177/0743558407303979. ISSN 0743-5584. S2CID 145644253. Tynes, Brendesha; Reynolds, Lindsay; Greenfield, Patricia M. (2004-11-11). "Adolescence, race, and ethnicity on the Internet: A comparison of discourse in monitored vs. unmonitored chat rooms". Journal of Applied Developmental Psychology. 25 (6): 667–684. doi:10.1016/j.appdev.2004.09.003. ISSN 0193-3973.