He spent two years as a lawyer with the Legal Aid Commission of Western Australia, where he completed his articled clerkship.

Ellison was elected as Senator for Western Australia in 1993, replacing Peter Durack,[6] and immediately became involved in parliamentary committees and inquiries across a range of portfolios.

[citation needed] He entered the Howard ministry as Parliamentary Secretary to the Minister for Health and Family Services and to the Attorney-General in 1997.

[citation needed] From March 2007 until the defeat of the Howard government in the 2007 election, Ellison was a member of cabinet as Minister for Human Services, overseeing the service delivery of Government agencies including Centrelink, Medicare and the Child Support Agency.

[6] He held the offices of Shadow Minister for Immigration and Citizenship, along with Manager of Opposition Business in the Senate from December 2007 to September 2008.

Ellison was announced as chancellor of the University of Notre Dame Australia in 2017, with effect from 1 January 2018.