Educated as a physician, Brundtland joined the Labour Party and entered the government in 1974 as Minister of the Environment.

Brundtland belonged to the moderate wing of her party and supported Norwegian membership in the European Union during the 1994 referendum.

Brundtland was born in Oslo in 1939, the daughter of physician and politician Gudmund Harlem and Inga Margareta Elisabet Brynolf (1918–2005).

Brundtland became leader of the Labour Party in 1981 and held the office until resigning in 1992, during her third term as prime minister.

For several years afterwards, Norway continued to have a high-profile involvement in promoting Israeli-Palestinian peace, though increasingly displaced by the United States from its role as the mediator.

Brundtland spearheaded the movement, now worldwide, to achieve the abolition of cigarette smoking by education, persuasion, and increased taxation.

Under Brundtland's leadership, the World Health Organization was criticized[9] for increased drug-company influence on the agency.

Brundtland was recognized in 2003 by Scientific American as their 'Policy Leader of the Year' for coordinating a rapid worldwide response to stem outbreaks of SARS.

In 2006 Brundtland was a member of the Panel of Eminent Persons who reviewed the work of the United Nations Conference on Trade and Development (UNCTAD).

In May 2007, UN Secretary-General Ban Ki-moon named Brundtland, as well as Ricardo Lagos (the former president of Chile), and Han Seung-soo (the former foreign minister of South Korea), to serve as UN Special Envoys for Climate Change.

[14] She was appointed Deputy Chair of the group in 2013 and was succeeded in this role by Ban Ki-moon and Graça Machel in 2018.

She had been on the island of Utøya hours before the massacre there to give a speech to the AUF camp; Breivik stated that he originally intended Brundtland to be the main target of the attack (along with Eskil Pedersen and Jonas Gahr Støre), but he had been delayed while travelling from Oslo.

[19] He told the court that he had planned to handcuff her and then record himself reading out a prepared text detailing her "crimes", before decapitating her on camera using a bayonet and uploading the footage to the internet.

Following media attention surrounding the matter, Brundtland decided to change residence once more, back to Norway, and she also announced that she would be paying for the treatments herself.