After training as a bookseller in Bad Godesberg and working as a representative for the German publishing house dtv Verlagsgesellschaft, she drew attention to herself under the pseudonym Dora Heldt with her novels about Christine and her idiosyncratic father Heinz.
Schmidt has been writing under the pseudonym Dora Heldt, the name of her grandmother, starting with her first novel, Ausgeliebt (2006).
A film adaptation of the book was made in the summer of 2009 for ZDF, starring Julia Stinshoff as Christine, Lambert Hamel as Heinz, and Steffen Groth as Johann.
With her novel Kein Wort zu Papa, she made it to number 1 on the bestseller list for the first time, in 2010.
She reached the top of the list again with her subsequent books Bei Hitze ist es wenigstens nicht kalt (2011), Wind aus West mit starken Böen (2014), Wir sind die Guten (2017), and Drei Frauen am See (2018).