[2] Following a year as an exchange student at Claremont High School in California in 1977,[3] and her final Abitur exams at the Käthe-Kollwitz-Gymnasium Neustadt in 1980, Dreyer started her English studies and Roman Catholic theology at the University of Mainz.

[5] Having served as State Minister of Social Affairs, Labor, Health and Demography since 2002, she was the designated successor of incumbent Minister-president Kurt Beck, who announced his upcoming resignation from the post on 28 September 2012.

In the 2016 state elections, Dreyer managed to convert her high personal approval ratings into a 36.2% win against her opponent Julia Klöckner,[7] improving her party's 2011 result by half a percentage point.

[9] During her second term in office, Dreyer's government decided to sell the state's 82.5 percent stake in the loss-making Frankfurt–Hahn Airport in western Germany to Chinese conglomerate HNA Group.

[11] In the negotiations to form a fourth coalition government under Merkel following the 2017 federal elections, she led the working group on health policy, alongside Hermann Gröhe and Georg Nüßlein.