He was first elected to the House of Representatives in 2001 as the Member for Burke.
At the 2004 Federal Election, Brendan was elected to the newly created electoral division of Gorton. He was re-elected at the 2007, 2010 and 2013 elections.
Brendan has served as Deputy Chair of the Public Works Committee and the Employment and Workplace Participation Committee. From January 2006 he chaired Labor's Industrial Relations Taskforce enquiring into the Howard Government's controversial Work Choices legislation.
Brendan served as the Shadow Parliamentary Secretary for Industrial Relations from December 2006 until the election of the Rudd Government, when he was appointed as Minister for Employment Participation. In a June 2009 reshuffle, Brendan became Minister for Home Affairs.
Following the 2010 federal election, Julia Gillard added the further responsibilities of Privacy and Freedom of Information to his portfolio. In December 2011, Brendan was appointed as the Minister for Human Services and Minister Assisting for School Education - a position he held for just over two months before a further reshuffle in early March 2012 saw Brendan enter Cabinet as Minister for Small Business and Minister for Housing and Homelessness.
In February 2013, Brendan was appointed the Minister for Immigration and Citizenship and in June 2013 was appointed the Minister for Employment, Skills and Training.
After the 2013 Federal Election, Brendan was appointed as the Shadow Minister for Employment and Workplace Relations.
Prior to entering Parliament, Brendan was a union official from 1986 to 2001, most recently Assistant National Secretary of the Australian Services Union from 1993 to 2001.
Brendan holds a BA and an LLB from Monash University, and a Diploma, Harvard Trade Union Program, Harvard University.