At the 2017 World Championships, Baker won three medals. She won silver in the 100-meter backstroke, bronze in the 200-meter backstroke, and gold in the 4x100-meter medley relay. Though she did not medal in the 50-meter backstroke, Baker broke Natalie Coughlin's American record in the event in the semifinals with a time of 27.48. Baker led off the women's 4x100-meter medley relay, with the team winning with a time of 3:51.55. The team of Baker, Lilly King, Kelsi Worrell, and Simone Manuel broke the 2012 world record of 3:52.05 set by Missy Franklin, Rebecca Soni, Dana Vollmer, and Allison Schmitt.