Fifield was born in Sydney, New South Wales, the son of two bank employees, and was educated at Barker College and the University of Sydney, where he graduated with a Bachelor of Arts. Between 1985 and 1987, Fifield served for three years in the Australian Army Reserve Psychology Corps.
Between 1988 to 1992, Fifield was a Senior Research Officer to the NSW Minister for Transport and Sydney's Olympic Bid, Bruce Baird; a Shadow Parliamentary Secretary for Industrial Relations' Policy Adviser, National's MP John Anderson during 1992; a Senior Policy Adviser to the Victorian Minister for Transport, Alan Brown from 1992 to 1996; and Senior Political Adviser to the Federal Treasurer, Peter Costello, from 1996 to 2003.
Since 1996, Fifield held a number of Liberal Party positions, including being a delegate to the Liberal Party Victorian State Council, since 1996; a delegate to the Liberal Party Policy Assembly, in 1996 and since 2004; a delegate to the Liberal Party Goldstein Electorate Council, between 1995 and 2003.
On 31 March 2004, Fifield was appointed by the Parliament of Victoria under section 15 of the Australian Constitution to fill the casual vacancy in the Australian Senate caused by the resignation in February 2004 of Richard Alston. Fifield was re-elected at the 2007 federal election. After the 2010 election, Fifield was appointed the Shadow Minister for Disabilities, Carers and the Voluntary Sector and Manager of Opposition Business in the Senate.
Throughout his political career, Fifield has been an advocate of voluntary student unionism, as well as allowing women to serve on the front lines of the Australian Defence Force. Along with Andrew Robb, he is also the co-publisher of The Party Room, a journal designed to promote new policy discussion within the Federal Coalition. Fifield has opposed federal money being spent on cycling infrastructure, and objected to part of the Rudd Government's $42 billion stimulus package being used for new cycleways and home insulation: "I don't think Bradford batts and bike paths is serious economic infrastructure. Call me crazy, but I don't think it is."
Following the 2013 federal election Fifield was appointed to the Abbott Ministry as the Assistant Minister for Social Services and the Manager of Government Business in the Senate.
Fifield replaced the current Australian Prime Minister, Malcolm Turnbull, as Minister for Communications, in September, 2015. He is currently deeply embroiled in a major Australian political controversy concerning his knowledge of police raids on his Opposition counterpart, Senator Stephen Conroy in the course of an election campaign, over leaks about alleged failures of the current Australian Prime Minister with respect to shortcomings of Australian internet infrastructure when Malcolm Turnbull was Minister for the same portfolio.