[4] Before his arrival in active politics, he was well known for his role during the 2012 Quebec student protests as co-spokesperson of the Coalition large de l'Association pour une solidarité syndicale étudiante (CLASSE), a broad coalition of student associations opposed to the $1,625 tuition hike introduced by Jean Charest's government.

Gabriel Nadeau-Dubois was born in a family of activists: his parents met in the Jeunesse Étudiante Chrétienne (Young Christian Students).

[5] At the Collège Regina Assumpta, a private school in Montreal, he obtained good grades but questioned everything, although he "was not a rebel", according to his father, Gilles Dubois.

[5] In Fall 2007, Gabriel Nadeau-Dubois joined the Association pour une solidarité syndicale étudiante (ASSÉ) as a student at the Collège de Bois-de-Boulogne.

[6] Gabriel Nadeau-Dubois first obtained a degree in Humanities from UQAM, then pursued a minor in philosophy at Université de Montréal.

[10] In June, he admitted that he was "psychologically tired" and announced that while he would request a renewal of his term as spokesperson at the CLASSE's congress, he would quit his position at the end of the strike, citing "both internal and external pressure".

In his resignation letter, published by Le Devoir, a left-leaning periodical, he expressed his opinion that the strike movement had raised deeper issues and "questioned corrupt institutions".

He nevertheless decided to press charges of contempt of court against Gabriel Nadeau-Dubois after having heard what he said to the TV channel RDI on May 13:[15] I think that it is completely legitimate for students to take action to make sure that the democratic choice to strike is respected.

And if that requires picket lines, we think that is a completely legitimate way to do it.Even though the injunction was no longer effective since Bill 78 was passed by the National Assembly on May 28, Article 32 of the special law[16] allows for contempt of court procedures to continue.

In October, 2016, writing for the majority, Justices Clément Gascon and Rosalie Abella stated that in Nadeau-Dubois's comments, picketing does not equal blocking classes, the latter being contra to the injunction.

[28] Speaking on the popular Quebec television show Tout le monde en parle on 23 November 2014, he announced he had donated his $25,000 Governor-General's Award prize money to fight the Energy East pipeline project, and that he has raised a further $385,000 to support the fight against the project, which is owned by TransCanada Pipelines and would funnel oil sands bitumen via Eastern Canada for export to foreign markets.

[29] In March 2017, Nadeau-Dubois decided to seek the nomination to be Québec solidaire's co-spokesperson, and also its candidate in the Montreal riding of Gouin vacated by Françoise David.

[32] A novel titled Tenir parole was published in Spring 2017, whose protagonist is an embattled Nadeau-Dubois during the 2012 student strike and which is narrated from a first-person perspective.