He started his journalistic career in London, as an economics correspondent for Investors Chronicle. In 1978 he joined the BBC as a reporter for The Money Programme, Newsnight, and then Panorama. In 1986 he moved to Australia and started work with the Australian Broadcasting Corporation.
From 1987 to 1994 he worked as an investigative reporter for the ABC's flagship current affairs program Four Corners. He specialised in reports on economic matters, government departmental failures and particularly corporate governance. A series of reports on now-disgraced businessman Alan Bond (and his company Bond Corporation) brought his work to national prominence in 1993. He also wrote The Rise and Fall of Alan Bond, regarded as the definitive account of Bond's demise. Likewise his report on the Wittenoom industrial disaster, "Blue Death" was similarly acclaimed.
In 1995, he joined the Seven Network to present a short-lived news program The Times. He stayed with the network, becoming presenter of the current affairs program Witness in 1997.
Paul moved back to the ABC to host the Media Watch program from 1999 to 2000. He was effectively sacked by controversial (and himself quickly replaced) ABC head Jonathon Shier after a hard-hitting interview with ABC Director Donald McDonald on the subject of government funding for the ABC.
For the next two years he wrote for The Sydney Morning Herald, winning an additional Walkley Award exposing a tax scam involving some prominent barristers in Sydney. He is now on the Walkley advisory board. He also wrote a book Rich Kids, documenting the collapse of One.Tel. In 2004 he moved to Channel 9 to work for 60 Minutes as an investigative reporter.
In 2006, Barry released a biography on Australian cricketer Shane Warne, called Spun Out. Extracts of the book were published in The Age's Good Weekend magazine, and the book has caused a degree of controversy. .
During October 2009, Barry was the subject of criticism from many Australian business identities for his upcoming unauthorised biography of media and gambling mogul James Packer. The book details relations between the younger Packer and his father Kerry, citing anonymous sources as stating the pair had a difficult relationship, and that James was "relieved" by his father's death. Business leaders and friends of the Packers including former Nine Network CEO Eddie McGuire and mining tycoon Andrew Forrest defended James Packer, claiming Barry had engaged in "sloppy" journalism.  Upon launching the book, Barry dismissed the criticism, calling the book "fair" and "considered" 
In June 2010, the ABC announced that Paul Barry will be returning as Media Watch's temporary host for three months while Holmes takes long service leave. Barry's tenure will begin in August. Holmes will return when the show does in 2011.
Paul Barry has been married twice and has six children.