Carsten Günter Erich Sieling (born 13 January 1959) is a German politician of the Social Democratic Party (SPD) who served as the President of the Senate and Mayor of Bremen from 2015 to 2019.

During the time of position held, he was his parliamentary group's rapporteur on consumer protection in financial services.

From 2012, he also served as deputy chairman of the German-British Parliamentary Friendship Group.

Sieling resigned from his seat in parliament to become President of the Senate and Mayor of Bremen in July 2015, succeeding Jens Böhrnsen.

In the negotiations to form a coalition government under the leadership of Chancellor Angela Merkel following the 2017 federal elections, Sieling was an SPD delegate in the working group on social affairs, led by Karl-Josef Laumann, Barbara Stamm and Andrea Nahles.