Dahrendorf was born in Hamburg, he served as member of the German Parliament from November 1932 to 22 June 1933. He was also several times a member of the Hamburg Parliament. He was the father of Ralf Dahrendorf, Baron Dahrendorf and Frank Dahrendorf.
In 1944 Dahrendorf was accused of treason at the Volksgerichtshof for his involvement in the 20 July plot alongside Julius Leber, Adolf Reichwein and Hermann Maaß. He was sentenced to 7 years imprisonment.
Dahrendorf died in Braunlage.