The Minister served in the State Parliament from 1993 to 2010.
As Minister for Planning and Infrastructure from 2001 to 2008, Ms MacTiernan was responsible for major projects across the State including the Mandurah rail line, the Forrest Highway, the Geraldton port and rail expansion and the Armadale town centre and Champion Lakes developments.
In 2011 she was elected Mayor of the City of Vincent and in 2013 was elected as the Member for Perth to the Federal Parliament, where she became Shadow Parliamentary Secretary for Western Australia and Deputy Chair of the Joint Standing Committee on Northern Australia.
After Ms MacTiernan decided not to recontest Perth in 2016, she was invited to re-join WA Labor in the Legislative Council.
After being elected in 2017, she was appointed Minister for Regional Development and Agriculture and Food and Minister Assisting the Minister for State Development, Jobs and Trade. In 2018 was given the Ports portfolio.
The Minister is committed to creating economic opportunity in our regional areas as well as bringing WA's agricultural sector into the 21st century through innovation and a focus on investing in science.