Jennifer Brady attended the University of California, Los Angeles, making her debut for the Bruins tennis team in 2013. She completed her sophomore year of studies before turning professional in 2015. That year she won the fourth and more recent ITF title at the $25k event in El Paso and made her WTA qualifying draw debut in Cincinnati (l. Falconi).
She made her first four main draw appearances at tour level in 2016 in Rio de Janeiro (as qualifier, l. Hercog in the first-round), Stanford (l. Cornet in the first-round), Montréal (as qualifier l. Svitolina in the first round) and Guangzhou where she registered her only WTA main draw wins of the year (d. Pivovarova and Kovinic, l. Konjuh in the quarter-finals). Thanks to those results, she finished the season at No.110 (up from No.229 in 2015).
In 2017 she won through qualifying at Australian Open and went on to become first major debutante to reach the round-16 at a Slam since Smitkova at 2014 Wimbledon. On her run she defeated Zanevska, Watson (after saving five match points) and No.14 seed Vesnina, collecting her maiden Top 20 win (l. Lucic-Baroni). She became the first American female qualifier to reach the fourth round at the Australian Open in Open Era and the sixth player to make the second week on her Australian Open debut since 1998 after Venus Williams (1998), Suárez Navarro (2009), Bouchard (2014), Gasparyan and Konta (2016).
She also advanced to the round 16 at 2017 US Open on her main draw debut in Flushing Meadows (l. top seed Karolina Pliskova), after scoring her second Top 50 win of career with defeat of No.25 Strycova in the second round.
That year, Brady reached her first WTA career semifinal in Hong Kong (l. eventual R-Up Gavrilova), reaching her career-high ranking at No.60 (October 16, 2017). She finished 2017 season inside the Top 100 for the first time at No.64.