In addition to his parliamentary work, he has been serving as the Secretary General of the CDU in North Rhine-Westphalia since 2022, under the leadership of chairman Hendrik Wüst.

[1] Ziemiak previously was the party's General Secretary on the national level from 8 December 2018 to 31 January 2022, under the leadership of Annegret Kramp-Karrenbauer and Armin Laschet.

From 2014 until 2018, he served as federal chairman of the Junge Union Deutschlands, in this capacity being a part of the CDU leadership under chairwoman Angela Merkel.

[2] Claiming partial German descent, they obtained citizenship under Germany's right of return laws and lived for a year in a refugee camp in Massen next to non-western asylum seekers.

[5] After graduation Ziemiak studied law at the Universität Osnabrück and the Westfälische Wilhelms-Universität Münster but failed the first legal exam on both attempts.

In the federal election 2017, Ziemiak ran as successor to Ingrid Fischbach in the constituency Herne – Bochum II,[11] but lost to Michelle Müntefering.

[13] In the negotiations to form a fourth coalition government under the leadership of Chancellor Angela Merkel following the 2017 federal elections, Ziemiak was part of the working group on families, women, seniors and youth, led by Annette Widmann-Mauz, Angelika Niebler and Katarina Barley.

[15] At the time of the vote, Ziemiak's nomination was widely interpreted as sign of Kramp-Karrenbauer' willingness to build bridges to the defeated conservatives around her opponents Friedrich Merz and Jens Spahn.

[16] Amid the COVID-19 pandemic in Germany, Ziemiak co-chaired – alongside Silvia Breher, Tobias Hans, Hendrik Hoppenstedt and Yvonne Magwas – the CDU’s first ever digital national convention in 2021.