Gabrielsen was born in
Slemmestad, in
Røyken in the present-day municipality of
Asker. He was assigned with the pulp mill
Tofte Industrier from 1984 to 1995, and was trained as process operator. From 1996 to 2003 he served as secretary for the
United Federation of Trade Unions, and from 2003 had other management roles for the federation. From 2013 he served as second deputy leader of the
Norwegian Confederation of Trade Unions, until he was elected leader at the congress in 2017. Gabrielsen died suddenly in his sleep on 9 March 2021 from heart failure. He was 53 years old. ==References==