Since 2003, Widmann-Mauz has been serving as deputy chairwoman of the CDU Baden-Württemberg, under the leadership of successive chairmen Erwin Teufel (2003-2005), Günther Oettinger (2005-2009), Stefan Mappus (2009-2011) and Thomas Strobl (since 2011).

From 2012 to 2022, Widmann-Mauz was a member of the CDU's national board under the leadership of successive chairs Angela Merkel (2012-2018), Annegret Kramp-Karrenbauer (2018–2021) and Armin Laschet (2021–2022).

[8] In the negotiations to form a fourth cabinet under Merkel following the 2017 federal elections, Widmann-Mauz led the working group on families, alongside Angelika Niebler and Katarina Barley.

[9] Following her party's defeat in the 2021 elections, Widmann-Mauz announced her candidacy as Vice President of the Bundestag; however, the CDU/CSU parliamentary group eventually nominated Yvonne Magwas for the position.

[28] Ahead of the Christian Democrats’ leadership election in 2018, Widmann-Mauz publicly endorsed Annegret Kramp-Karrenbauer to succeed Angela Merkel as the party's chair.