Born in the neighbourhood of Grünerløkka, Oslo in 1943 during Norway's occupation by Nazi Germany, she was raised by a tailor father and a hairdresser mother and grew up in what was then a working-class district of the inner city.

In 2002, Joly was asked by the Norwegian Minister of Justice, Odd Einar Dørum, to accept a three-year position as a special advisor on corruption.

[3] On 7 June 2009, Joly was elected as a French member of the European Parliament on the Ile de France "Europe Écologie" list on which she was second after Daniel Cohn-Bendit.

[17] When Joly filed a lawsuit in December 2015 on behalf of the company's works council, a preliminary tax inquiry into McDonald's was opened in early 2015.

[19] In 2011, Joly competed in the primaries of Europe Écologie–The Greens against Nicolas Hulot, Stéphane Lhomme and Henri Stoll to represent the party at the 2012 presidential election.

[25] In June 2010, Joly was sent a court summons by Nadine Berthélémy-Dupuis, an investigating magistrate in Paris, following a legal complaint from David Douillet, a retired sportsman and a national member of parliament from France's then-ruling Union for a Popular Movement.

[26] In November 2011, Joly was criticized for her support of the Greens' deal with the Socialist Party under which they gained safe seats in parliament, in exchange for accepting a slow-motion plan to reduce nuclear energy use to 50 percent of electricity generation by 2025.

[27] During her 2012 presidential campaign, Joly led reporters on a tour of sites linked to bad publicity or sleaze allegations around then-president Nicolas Sarkozy.

Her tour included a Champs-Élysées nightspot in which Sarkozy feted his 2007 victory with millionaire friends, and the home of L'Oréal heiress Liliane Bettencourt, at the centre of an investigation into illegal alleged cash contributions to his 2007 campaign.