Born in Melbourne, she moved to Perth to study at the University of Western Australia, graduating with a Bachelor of Arts and later with a law degree.

She became a shadow minister in October 1994, and she was transferred to the Legislative Assembly at the 1996 state election, winning the seat of Armadale.

She resigned from state parliament in 2010 in order to contest the seat of Canning in that year's federal election.

At the 2021 state election, she transferred to the South West Region and became the minister for hydrogen industry but relinquished ports.

She was the subject of controversy in 2022 when she made comments saying that the Indonesian foot-and-mouth disease outbreak would be good for Australia.

Alannah Joan Geraldine MacTiernan was born on 10 January 1953 in East Melbourne, Victoria, Australia.

[1][5][6] Before her election to parliament, she was a member of several community organisations, including the Perth Theatre Trust, Rod Evans Senior Citizens Centre, the Irish Club of WA, and the Irish–Australian Congress.

From 1975 to 1994, she was involved in the University Women's Soccer Club, including as president, secretary, treasurer and patron.

[1][6] In her inaugural speech, she criticised the existence of the Legislative Council, saying: I propose to commence my career in this place by putting on record my belief that this House is an anachronism, and that its existence falsely suggests that important checks and balances required in the parliamentary democracy are in place.

This House has always fiercely protected property and conservative rural interests, which is hardly surprising given that it is the direct spiritual descendant of the House of Lords... [and] the Legislative Council has not during any period of conservative government this century provided any real fetter on the power of the Government of the day.

She resigned from the Legislative Council on 21 November 1996 and retained the seat of Armadale for the Labor Party at the election on 14 December.

[1] Labor won the February 2001 state election, and the newly appointed premier Geoff Gallop made MacTiernan the Minister for Planning and Infrastructure.

She retained this role for the following eight years that Labor was in power, including when Gallop resigned and was replaced as premier by Alan Carpenter.

In July 2001, Cabinet approved the rerouting of the line as a direct route south from the Perth central business district (CBD) along the Kwinana Freeway.

This made the railway more expensive than the previous plan, but resulted in a faster travel time as well as serving new areas.

[19][20][21] She refused to build Roe 8, an extension of the highway west of the Kwinana Freeway through the Beeliar Wetlands, however, due to the environmental impact.

[25] In December 2006, she approved of the awarding of a $511 million contract for the construction of the New Perth Bunbury Highway project.

[31][32] She pulled out of the leadership contest when it became clear she did not have the support of caucus, and so Eric Ripper was elected leader.

[64] Amid speculation that she would attempt to challenge Mark McGowan to become leader of the Labor Party in Western Australia, she denied she was going to do that, but did not rule out returning to state politics.

[65][66] After Ken Travers resigned from the Legislative Council in August 2016, McGowan announced MacTiernan as his preferred choice as the first candidate on the Labor Party's ticket for the North Metropolitan Region at the March 2017 state election.

In the meantime, Laine McDonald replaced Travers as she was the next candidate on Labor's North Metropolitan ticket.

[1][71][72] Ahead of the 2021 state election, MacTiernan replaced Adele Farina as the second candidate on the Labor Party's ticket for the South West Region.

[78] In July 2022, MacTiernan attracted controversy due to her comments in response to the 2022 Indonesian foot-and-mouth disease outbreak.

Federal Liberal MP Rick Wilson said that she should be sacked, saying "for a so-called minister for agriculture, to treat this issue in such a cavalier and careless manner indicates she is not fit in any way, shape or form to hold her current position".

[80][81] State shadow agriculture minister and Nationals MLA Colin de Grussa said the comments were a "slap in the face" and showed "disdain" for farmers.

[80] Federal Nationals leader David Littleproud said "Alannah MacTiernan’s comments are the most abhorrent I’ve heard from an Australian agriculture minister".

[82] Pastoralists and Graziers Association president Tony Seabrook, WA Farmers Federation chief executive Trevor Whittington, and WA Farmers president John Hassell also criticised the comments, although Seabrook held back from calling for her to resign as he thought there was no other suitable Labor MP.

MacTiernan apologised,[84][85] Days later, she confirmed her intention to retire at the 2025 state election, but continue in the ministry until then.

Dawkins is suspended from the Labor Party for being charged with 43 counts of breaching a family violence restraining order.