Schmidt became a SPD member when she was 16. As a Juso member, she acted as an observer in the 1995–96 South African municipal elections. While she was preparing a PhD thesis about the history of the SPD, she was offered a job in the office of Landtag of Hesse member Andrea Ypsilanti. She continued as Ypsilanti's assistant when Ypsilanti became state SPD leader, and later became an assistant to her successor, Thorsten Schäfer-Gümbel. In the 2009 and 2013 federal elections, she was the SPD candidate for the electoral district, losing out to the CDU candidate each time. However, in 2013, placed sixth on the SPD party list for Hesse, she was elected to the Bundestag. She also became a member of the SPD executive committee. In 2017, she was re-elected, placed fourth on the SPD list for Hesse. She has since been serving on the Committee on Labor and Social Affairs.