He attended school locally, having many jobs including: work in fishing, as a coal miner and on a building site.

Over a 9- to 10-month period, Bratteli travelled with whalers to Antarctica, where he worked in a guano factory at South Georgia Island.

He was arrested by agents of Nazi Germany in 1942, and was a Nacht und Nebel prisoner of various German concentration camps; including Natzweiler-Struthof, from 1943 to 1945.

[2] He was liberated from Vaihingen an der Enz concentration camp on 5 April 1945, by the Swedish Red Cross White Buses along with fifteen other Norwegians who had survived.

In September 1963, when Gerhardsen's fourth cabinet was formed, Bratteli was again made Minister of Transport and Communications, a post he held until 1964.

The centre-right cabinet of Borten held office from 1965 to 1971, but when it collapsed, Bratteli became Prime Minister.

In social policy, Bratteli's premiership saw the passage of a law in June 1972 that lowered the pension age to 67.