He completed an apprenticeship as a car mechanic and worked in the catering industry before being elected mayor of Ebendorf (Barleben) in 1990.

In the German federal elections on 27 September 2009, Behrens won the direct mandate in the Bundestag constituency Börde - Jerichower Land and became a member of the German Bundestag.

[2] In the 2013 federal elections, Behrens again won the direct mandate for his constituency.

He subsequently became a member of the Committee on Transport and Digital Infrastructure, where he served as his parliamentary group’s rapporteur on for accessibility and consumer protection, and a deputy member of the Committee on Family, Senior Citizens, Women and Youth.

[1] In addition to his committee assignments, Behrens was a member of the German-Canadian Parliamentary Friendship Group and of the Parliamentary Friendship Group for the States of East Africa, which is in charge of maintaining inter-parliamentary relations with Ethiopia, Burundi, Djibouti, Eritrea, Kenya, Rwanda, Somalia, Sudan and Uganda.