He studied law at the universities of Breslau and Kiel.
From 1953 to 1965 he served as Minister of Foreign Affairs of East Germany (German Democratic Republic). After his study he worked as a lawyer in Breslau and in 1930, he joined the Communist Party of Germany. After the Nazis seized power in 1933 he was forced to quit as a lawyer: Bolz went to Moscow, finding work as a teacher at the Marx-Engels Institute.
From 1941 to 1945 he was headteacher of the so-called Antifascist School, where German POWs were taught to become antifascists.
During his stay at the Soviet Union, he became a Soviet citizen and retained dual citizenship. From 1948 to 1972 he was the chairman of the NDPD. From 1950 to 1967 he was one of the Deputy Prime Ministers of the German Democratic Republic. In 1953, being the successor of Foreign Minister Anton Ackermann.
He stayed in the office until 1965. He also acted as the chairman of Society for German-Soviet Friendship from 1968 to 1978.
Bolz died on 28 December 1986 in East Berlin at the age of 83.
In 1947, he returned to Germany and joined the East German Socialist Unity Party, but in 1948 he founded the Communist sponsored National Democratic Party of Germany (NDPD). From 1950 to his death he was a member of the Presidium of the National Front.
National Committee for a Free Germany]
Many members of the NDPD were former Nazis and former Wehrmacht officers. In 1949 he became a member of the People"s Chamber (Parliament) and from 1949 to 1953 he was Minister of Reconstruction.