Marcin Piotr Kierwiński (born 22 August 1976) is a Polish politician, local government official, Deputy Marshal of the 3rd and 4th term of Masovia from 2010 to 2011, Member of Parliament of the 7th, 8th and 9th term, secretary of state in the Prime Minister's Chancellery and head of the political cabinet of Prime Minister Ewa Kopacz in 2015 and general secretary of the Civic Platform from 2020.

Elected as a Member of the European Parliament in 2024.^[1]