Prior to entering politics, Kearney served as president of the Australian Council of Trade Unions (ACTU) from 2010 to 2018.

Gerardine Mary Kearney was born on 29 October 1963 in East Melbourne, Victoria, Australia; she grew up in Richmond as the second-youngest of nine siblings.

[7] In December 2011, Kearney and other trade unionists were deported from Fiji under the emergency laws put in place following the Fijian constitutional crisis of 2009.

[12] In July 2012, immigration minister Chris Bowen created the Ministerial Advisory Council on Skilled Migration (MACSM) and appointed Kearney as one of its nine members.

[17] In May 2013, in the lead up to the 2013 federal election, Kearney said she was considering nominating herself for Labor preselection in the Division of Batman, a seat that was being vacated following the retirement of Martin Ferguson.

[21] In February 2018, a by-election was announced in the seat of Batman following the resignation of David Feeney due to the 2017–2018 Australian parliamentary eligibility crisis.

[25][26] The Australian Conservation Foundation distributed material stating only the Greens would "stop Adani's mine from going ahead".

[28] During the by-election campaign, Kearney received the personal endorsement of former Prime Minister Julia Gillard, who wrote a letter that was distributed to 36,000 houses within the electorate.

[31] In her maiden speech as an MP, Gerardine Kearney advocated for a "humane refugee policy" in Australia and called for an end to offshore detention of asylum seekers.

[36] In June 2021, Kearney and two other female Labor MPs wrote to the Prime Minister Scott Morrison, calling for him to dismiss the committee chair Andrew Laming over his behaviour towards women.

[43] On 15 November 2023, fake corpses were placed outside the electorate offices of Kearney and other MPs as part of a protest against the government's position on the 2023 Israel–Hamas war.

[50][51] On 4 September 2023 on the Australian political television talk show Q+A, Kearney said: This [the Voice] was a very generous request made of us by First Nations people, through a very broad process of consultation, and that culminated in the Uluru Statement from the Heart, which asked us to do this ...

[53] Along with Health Minister Mark Butler, Kearney set up and now chairs the federal government HIV taskforce.