Weiss first became a member of the Bundestag in the 2009 German federal election.[1] In her first term from 2009 until 2013, she served on the Committee on Petitions; the Committee on Economic Cooperation and Development; the Subcommittee on Health in Developing Countries; and the Subcommittee on Civilian Crisis Prevention.
In the negotiations to form a Grand Coalition of Chancellor Angela Merkel's Christian Democrats (CDU together with the Bavarian CSU) and the SPD following the 2013 federal elections, Weiss was part of the CDU/CSU delegation in the working group on families, women and equality, led by Annette Widmann-Mauz and Manuela Schwesig. From 2014 until 2018, she was one of the deputy chairs of the CDU/CSU parliamentary group, under the leadership of chairman Volker Kauder.
In the coalition talks following the 2017 federal elections, Weiss was part of the working group on social affairs, this time led Andrea Nahles, Karl-Josef Laumann and Barbara Stamm. From 2018 until 2021, she served (alongside Thomas Gebhart) as one of two Parliamentary State Secretaries to the Federal Minister for Health Jens Spahn.
Since leaving government, Weiss has been serving on the Committee on Human Rights and Humanitarian Aid. In addition to his committee assignments, she has been a member of the German delegation to the Parliamentary Assembly of the Council of Europe (PACE) since 2022. In the Assembly, she serves on the Committee on Migration, Refugees and Displaced Persons.[2]